feat(devcontainer): add separate secure customer profile (#10431)

## Description

Keeps the existing Codex contributor devcontainer in place and adds a
separate secure profile for customer use.

## What changed

- leaves `.devcontainer/devcontainer.json` and the contributor
`Dockerfile` aligned with `main`
- adds `.devcontainer/devcontainer.secure.json` and
`.devcontainer/Dockerfile.secure`
- adds secure-profile bootstrap scripts:
  - `post_install.py`
  - `post-start.sh`
  - `init-firewall.sh`
- updates `.devcontainer/README.md` to explain when to use each path

## Secure profile behavior

The new secure profile is opt-in and is meant for running Codex in a
stricter project container:

- preinstalls the Codex CLI plus common build tools
- uses persistent volumes for Codex state, Cargo, Rustup, and GitHub
auth
- applies an allowlist-driven outbound firewall at startup
- blocks IPv6 by default so the allowlist cannot be bypassed via AAAA
routes
- keeps the stricter networking isolated from the default contributor
workflow

## Resulting behavior

- `devcontainer.json` remains the low-friction Codex contributor setup
- `devcontainer.secure.json` is the customer-facing secure option
- the repo supports both workflows without forcing the secure profile on
Codex contributors

.devcontainer/devcontainer.secure.json

@@ -0,0 +1,76 @@
+{
+  "$schema": "https://raw.githubusercontent.com/devcontainers/spec/main/schemas/devContainer.schema.json",
+  "name": "Codex (Secure)",
+  "build": {
+    "dockerfile": "Dockerfile.secure",
+    "context": "..",
+    "args": {
+      "TZ": "${localEnv:TZ:UTC}",
+      "NODE_MAJOR": "22",
+      "RUST_TOOLCHAIN": "1.92.0",
+      "CODEX_NPM_VERSION": "latest"
+    }
+  },
+  "runArgs": [
+    "--cap-add=NET_ADMIN",
+    "--cap-add=NET_RAW"
+  ],
+  "init": true,
+  "updateRemoteUserUID": true,
+  "remoteUser": "vscode",
+  "workspaceMount": "source=${localWorkspaceFolder},target=/workspace,type=bind,consistency=delegated",
+  "workspaceFolder": "/workspace",
+  "mounts": [
+    "source=codex-commandhistory-${devcontainerId},target=/commandhistory,type=volume",
+    "source=codex-home-${devcontainerId},target=/home/vscode/.codex,type=volume",
+    "source=codex-gh-${devcontainerId},target=/home/vscode/.config/gh,type=volume",
+    "source=codex-cargo-registry-${devcontainerId},target=/home/vscode/.cargo/registry,type=volume",
+    "source=codex-cargo-git-${devcontainerId},target=/home/vscode/.cargo/git,type=volume",
+    "source=codex-rustup-${devcontainerId},target=/home/vscode/.rustup,type=volume",
+    "source=${localEnv:HOME}/.gitconfig,target=/home/vscode/.gitconfig,type=bind,readonly"
+  ],
+  "containerEnv": {
+    "RUST_BACKTRACE": "1",
+    "CODEX_UNSAFE_ALLOW_NO_SANDBOX": "1",
+    "CODEX_ENABLE_FIREWALL": "1",
+    "CODEX_INCLUDE_GITHUB_META_RANGES": "1",
+    "OPENAI_ALLOWED_DOMAINS": "api.openai.com auth.openai.com github.com api.github.com codeload.github.com raw.githubusercontent.com objects.githubusercontent.com crates.io index.crates.io static.crates.io static.rust-lang.org registry.npmjs.org pypi.org files.pythonhosted.org",
+    "CARGO_TARGET_DIR": "/workspace/.cache/cargo-target",
+    "GIT_CONFIG_GLOBAL": "/home/vscode/.gitconfig.local",
+    "COREPACK_ENABLE_DOWNLOAD_PROMPT": "0",
+    "PYTHONDONTWRITEBYTECODE": "1",
+    "PIP_DISABLE_PIP_VERSION_CHECK": "1"
+  },
+  "remoteEnv": {
+    "OPENAI_API_KEY": "${localEnv:OPENAI_API_KEY}"
+  },
+  "postCreateCommand": "python3 /opt/post_install.py",
+  "postStartCommand": "bash /opt/post_start.sh",
+  "waitFor": "postStartCommand",
+  "customizations": {
+    "vscode": {
+      "settings": {
+        "terminal.integrated.defaultProfile.linux": "zsh",
+        "terminal.integrated.profiles.linux": {
+          "bash": {
+            "path": "bash",
+            "icon": "terminal-bash"
+          },
+          "zsh": {
+            "path": "zsh"
+          }
+        },
+        "files.trimTrailingWhitespace": true,
+        "files.insertFinalNewline": true,
+        "files.trimFinalNewlines": true
+      },
+      "extensions": [
+        "openai.chatgpt",
+        "rust-lang.rust-analyzer",
+        "tamasfe.even-better-toml",
+        "vadimcn.vscode-lldb",
+        "ms-azuretools.vscode-docker"
+      ]
+    }
+  }
+}