sandboxing: intersect permission profiles semantically (#18275)

## Why

Permission approval responses must not be able to grant more access than
the tool requested. Moving this flow to `PermissionProfile` means the
comparison must be profile-shaped instead of `SandboxPolicy`-shaped, and
cwd-relative special paths such as `:cwd` and `:project_roots` must stay
anchored to the turn that produced the request.

## What changed

This implements semantic `PermissionProfile` intersection in
`codex-sandboxing` for file-system and network permissions. The
intersection accepts narrower path grants, rejects broader grants,
preserves deny-read carve-outs and glob scan depth, and materializes
cwd-dependent special-path grants to absolute paths before they can be
recorded for reuse.

The request-permissions response paths now use that intersection
consistently. App-server captures the request turn cwd before waiting
for the client response, includes that cwd in the v2 approval params,
and core stores the requested profile plus cwd for direct TUI/client
responses and Guardian decisions before recording turn- or
session-scoped grants. The TUI app-server bridge now preserves the
app-server request cwd when converting permission approval params into
core events.

## Verification

- `cargo test -p codex-sandboxing intersect_permission_profiles --
--nocapture`
- `cargo test -p codex-app-server request_permissions_response --
--nocapture`
- `cargo test -p codex-core
request_permissions_response_materializes_session_cwd_grants_before_recording
-- --nocapture`
- `cargo check -p codex-tui --tests`
- `cargo check --tests`
- `cargo test -p codex-tui
app_server_request_permissions_preserves_file_system_permissions`

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -3432,6 +3432,9 @@
     "PermissionsRequestApprovalParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "properties": {
+        "cwd": {
+          "$ref": "#/definitions/v2/AbsolutePathBuf"
+        },
         "itemId": {
           "type": "string"
         },
@@ -3452,6 +3455,7 @@
         }
       },
       "required": [
+        "cwd",
         "itemId",
         "permissions",
         "threadId",