fix: pin inputs (#17471)

## Summary
- Pin Rust git patch dependencies to immutable revisions and make
cargo-deny reject unknown git and registry sources unless explicitly
allowlisted.
- Add checked-in SHA-256 coverage for the current rusty_v8 release
assets, wire those hashes into Bazel, and verify CI override downloads
before use.
- Add rusty_v8 MODULE.bazel update/check tooling plus a Bazel CI guard
so future V8 bumps cannot drift from the checked-in checksum manifest.
- Pin release/lint cargo installs and all external GitHub Actions refs
to immutable inputs.

## Future V8 bump flow
Run these after updating the resolved `v8` crate version and checksum
manifest:

```bash
python3 .github/scripts/rusty_v8_bazel.py update-module-bazel
python3 .github/scripts/rusty_v8_bazel.py check-module-bazel
```

The update command rewrites the matching `rusty_v8_<crate_version>`
`http_file` SHA-256 values in `MODULE.bazel` from
`third_party/v8/rusty_v8_<crate_version>.sha256`. The check command is
also wired into Bazel CI to block drift.

## Notes
- This intentionally excludes RustSec dependency upgrades and
bubblewrap-related changes per request.
- The branch was rebased onto the latest origin/main before opening the
PR.

## Validation
- cargo fetch --locked
- cargo deny check advisories
- cargo deny check
- cargo deny check sources
- python3 .github/scripts/rusty_v8_bazel.py check-module-bazel
- python3 .github/scripts/rusty_v8_bazel.py update-module-bazel
- python3 -m unittest discover -s .github/scripts -p
'test_rusty_v8_bazel.py'
- python3 -m py_compile .github/scripts/rusty_v8_bazel.py
.github/scripts/rusty_v8_module_bazel.py
.github/scripts/test_rusty_v8_bazel.py
- repo-wide GitHub Actions `uses:` audit: all external action refs are
pinned to 40-character SHAs
- yq eval on touched workflows and local actions
- git diff --check
- just bazel-lock-check

## Hash verification
- Confirmed `MODULE.bazel` hashes match
`third_party/v8/rusty_v8_146_4_0.sha256`.
- Confirmed GitHub release asset digests for denoland/rusty_v8
`v146.4.0` and openai/codex `rusty-v8-v146.4.0` match the checked-in
hashes.
- Streamed and SHA-256 hashed all 10 `MODULE.bazel` rusty_v8 asset URLs
locally; every downloaded byte stream matched both `MODULE.bazel` and
the checked-in manifest.

## Pin verification
- Confirmed signing-action pins match the peeled commits for their tag
comments: `sigstore/cosign-installer@v3.7.0`, `azure/login@v2`, and
`azure/trusted-signing-action@v0`.
- Pinned the remaining tag-based action refs in Bazel CI/setup:
`actions/setup-node@v6`, `facebook/install-dotslash@v2`,
`bazelbuild/setup-bazelisk@v3`, and `actions/cache/restore@v5`.
- Normalized all `bazelbuild/setup-bazelisk@v3` refs to the peeled
commit behind the annotated tag.
- Audited Cargo git dependencies: every manifest git dependency uses
`rev` only, every `Cargo.lock` git source has `?rev=<sha>#<same-sha>`,
and `cargo deny check sources` passes with `required-git-spec = "rev"`.
- Shallow-fetched each distinct git dependency repo at its pinned SHA
and verified Git reports each object as a commit.

.github/scripts/rusty_v8_module_bazel.py

@@ -0,0 +1,230 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass
+from pathlib import Path
+
+
+SHA256_RE = re.compile(r"[0-9a-f]{64}")
+HTTP_FILE_BLOCK_RE = re.compile(r"(?ms)^http_file\(\n.*?^\)\n?")
+
+
+class RustyV8ChecksumError(ValueError):
+    pass
+
+
+@dataclass(frozen=True)
+class RustyV8HttpFile:
+    start: int
+    end: int
+    block: str
+    name: str
+    downloaded_file_path: str
+    sha256: str | None
+
+
+def parse_checksum_manifest(path: Path) -> dict[str, str]:
+    try:
+        lines = path.read_text(encoding="utf-8").splitlines()
+    except FileNotFoundError as exc:
+        raise RustyV8ChecksumError(f"missing checksum manifest: {path}") from exc
+
+    checksums: dict[str, str] = {}
+    for line_number, line in enumerate(lines, 1):
+        if not line.strip():
+            continue
+        parts = line.split()
+        if len(parts) != 2:
+            raise RustyV8ChecksumError(
+                f"{path}:{line_number}: expected '<sha256>  <filename>'"
+            )
+        checksum, filename = parts
+        if not SHA256_RE.fullmatch(checksum):
+            raise RustyV8ChecksumError(
+                f"{path}:{line_number}: invalid SHA-256 digest for {filename}"
+            )
+        if not filename or filename in {".", ".."} or "/" in filename:
+            raise RustyV8ChecksumError(
+                f"{path}:{line_number}: expected a bare artifact filename"
+            )
+        if filename in checksums:
+            raise RustyV8ChecksumError(
+                f"{path}:{line_number}: duplicate checksum for {filename}"
+            )
+        checksums[filename] = checksum
+
+    if not checksums:
+        raise RustyV8ChecksumError(f"empty checksum manifest: {path}")
+    return checksums
+
+
+def string_field(block: str, field: str) -> str | None:
+    # Matches one-line string fields inside http_file blocks, e.g. `sha256 = "...",`.
+    match = re.search(rf'^\s*{re.escape(field)}\s*=\s*"([^"]+)",\s*$', block, re.M)
+    if match:
+        return match.group(1)
+    return None
+
+
+def rusty_v8_http_files(module_bazel: str, version: str) -> list[RustyV8HttpFile]:
+    version_slug = version.replace(".", "_")
+    name_prefix = f"rusty_v8_{version_slug}_"
+    entries = []
+    for match in HTTP_FILE_BLOCK_RE.finditer(module_bazel):
+        block = match.group(0)
+        name = string_field(block, "name")
+        if not name or not name.startswith(name_prefix):
+            continue
+        downloaded_file_path = string_field(block, "downloaded_file_path")
+        if not downloaded_file_path:
+            raise RustyV8ChecksumError(
+                f"MODULE.bazel {name} is missing downloaded_file_path"
+            )
+        entries.append(
+            RustyV8HttpFile(
+                start=match.start(),
+                end=match.end(),
+                block=block,
+                name=name,
+                downloaded_file_path=downloaded_file_path,
+                sha256=string_field(block, "sha256"),
+            )
+        )
+    return entries
+
+
+def module_entry_set_errors(
+    entries: list[RustyV8HttpFile],
+    checksums: dict[str, str],
+    version: str,
+) -> list[str]:
+    errors = []
+    if not entries:
+        errors.append(f"MODULE.bazel has no rusty_v8 http_file entries for {version}")
+        return errors
+
+    module_files: dict[str, RustyV8HttpFile] = {}
+    duplicate_files = set()
+    for entry in entries:
+        if entry.downloaded_file_path in module_files:
+            duplicate_files.add(entry.downloaded_file_path)
+        module_files[entry.downloaded_file_path] = entry
+
+    for filename in sorted(duplicate_files):
+        errors.append(f"MODULE.bazel has duplicate http_file entries for {filename}")
+
+    for filename in sorted(set(module_files) - set(checksums)):
+        entry = module_files[filename]
+        errors.append(f"MODULE.bazel {entry.name} has no checksum in the manifest")
+
+    for filename in sorted(set(checksums) - set(module_files)):
+        errors.append(f"manifest has {filename}, but MODULE.bazel has no http_file")
+
+    return errors
+
+
+def module_checksum_errors(
+    entries: list[RustyV8HttpFile],
+    checksums: dict[str, str],
+) -> list[str]:
+    errors = []
+    for entry in entries:
+        expected = checksums.get(entry.downloaded_file_path)
+        if expected is None:
+            continue
+        if entry.sha256 is None:
+            errors.append(f"MODULE.bazel {entry.name} is missing sha256")
+        elif entry.sha256 != expected:
+            errors.append(
+                f"MODULE.bazel {entry.name} has sha256 {entry.sha256}, "
+                f"expected {expected}"
+            )
+    return errors
+
+
+def raise_checksum_errors(message: str, errors: list[str]) -> None:
+    if errors:
+        formatted_errors = "\n".join(f"- {error}" for error in errors)
+        raise RustyV8ChecksumError(f"{message}:\n{formatted_errors}")
+
+
+def check_module_bazel_text(
+    module_bazel: str,
+    checksums: dict[str, str],
+    version: str,
+) -> None:
+    entries = rusty_v8_http_files(module_bazel, version)
+    errors = [
+        *module_entry_set_errors(entries, checksums, version),
+        *module_checksum_errors(entries, checksums),
+    ]
+    raise_checksum_errors("rusty_v8 MODULE.bazel checksum drift", errors)
+
+
+def block_with_sha256(block: str, checksum: str) -> str:
+    sha256_line_re = re.compile(r'(?m)^(\s*)sha256\s*=\s*"[0-9a-f]+",\s*$')
+    if sha256_line_re.search(block):
+        return sha256_line_re.sub(
+            lambda match: f'{match.group(1)}sha256 = "{checksum}",',
+            block,
+            count=1,
+        )
+
+    downloaded_file_path_match = re.search(
+        r'(?m)^(\s*)downloaded_file_path\s*=\s*"[^"]+",\n',
+        block,
+    )
+    if not downloaded_file_path_match:
+        raise RustyV8ChecksumError("http_file block is missing downloaded_file_path")
+    insert_at = downloaded_file_path_match.end()
+    indent = downloaded_file_path_match.group(1)
+    return f'{block[:insert_at]}{indent}sha256 = "{checksum}",\n{block[insert_at:]}'
+
+
+def update_module_bazel_text(
+    module_bazel: str,
+    checksums: dict[str, str],
+    version: str,
+) -> str:
+    entries = rusty_v8_http_files(module_bazel, version)
+    errors = module_entry_set_errors(entries, checksums, version)
+    raise_checksum_errors("cannot update rusty_v8 MODULE.bazel checksums", errors)
+
+    updated = []
+    previous_end = 0
+    for entry in entries:
+        updated.append(module_bazel[previous_end : entry.start])
+        updated.append(
+            block_with_sha256(entry.block, checksums[entry.downloaded_file_path])
+        )
+        previous_end = entry.end
+    updated.append(module_bazel[previous_end:])
+    return "".join(updated)
+
+
+def check_module_bazel(
+    module_bazel_path: Path,
+    manifest_path: Path,
+    version: str,
+) -> None:
+    checksums = parse_checksum_manifest(manifest_path)
+    module_bazel = module_bazel_path.read_text(encoding="utf-8")
+    check_module_bazel_text(module_bazel, checksums, version)
+    print(f"{module_bazel_path} rusty_v8 {version} checksums match {manifest_path}")
+
+
+def update_module_bazel(
+    module_bazel_path: Path,
+    manifest_path: Path,
+    version: str,
+) -> None:
+    checksums = parse_checksum_manifest(manifest_path)
+    module_bazel = module_bazel_path.read_text(encoding="utf-8")
+    updated_module_bazel = update_module_bazel_text(module_bazel, checksums, version)
+    if updated_module_bazel == module_bazel:
+        print(f"{module_bazel_path} rusty_v8 {version} checksums are already current")
+        return
+    module_bazel_path.write_text(updated_module_bazel, encoding="utf-8")
+    print(f"updated {module_bazel_path} rusty_v8 {version} checksums")