Strip GitHub auth from runner job environment

[jmcte]

Motivation

• Public/selected Synology runner containers previously inherit long-lived GitHub credentials (GITHUB_PAT and GitHub App envs) which job-level processes can read, creating a credential-exposure vulnerability.

Description

• Add a new sanitized job launch helper run_runner_job_bash in docker/runner-entrypoint.sh that launches ./run.sh with env -u to unset GITHUB_PAT, GITHUB_APP_ID, GITHUB_APP_INSTALLATION_ID, and GITHUB_APP_PRIVATE_KEY before executing the job process.
• Switch the runner job start path to use the sanitized run_runner_job_bash so registration/cleanup still use the existing credential-bearing path while jobs run without inherited GitHub auth.
• Extend the smoke runner stub scripts/smoke/actions-runner/run.sh to fail if any GitHub auth env vars are present and to record the sanitized state, and add an assertion to scripts/smoke-test.sh to verify the job process sees github auth: unset.
• Key files changed: docker/runner-entrypoint.sh, scripts/smoke/actions-runner/run.sh, and scripts/smoke-test.sh.

Testing

• Ran the TypeScript build and unit tests with pnpm --silent build && pnpm --silent test, and all tests passed (48 test files, 263 tests succeeded).
• Performed a shell syntax check bash -n on modified shell scripts which succeeded.
• Executed the smoke harness pnpm --silent smoke-test but it was blocked in this environment because Docker is not installed (docker: command not found), so full smoke execution could not complete here.

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Codex Task

[chatgpt-codex-connector]

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[athena-omt]

Athena review: approves. The change is focused, tests cover the new guard, and I don't see a blocker in the diff.

[pheidon]

Pheidon review: approves. The change is focused, tests cover the new guard, and I don't see a blocker in the diff.

[athena-omt]

I checked the PR branch in the actual worktree and the fix looks complete. The runner entrypoint now stashes GitHub auth only for cleanup, unsets it before launching the job process, and the smoke harness asserts the job sees GitHub auth as unset. I also sanity-checked the CI switch to ./actions/setup-shell-safe-node; it matches the repository’s wrapper and pinned Node version.

No new blocker found.

[athena-omt]

APPROVE

I synced the PR mirror and reviewed the live diff in the worker worktree. The runner entrypoint now strips GitHub auth before launching the job process while preserving the credential-bearing cleanup path, and the smoke harness plus workflow tests line up with that behavior. I did not find a new merge blocker beyond the existing queue state.