Fix: #1 - Add a bunch of random comments to Bigquery - #2

- Conduct 2 independent Gemini reviews per round locally within Jetski (up to 3 rounds or until no high-priority issues come up) instead of repeatedly triggering `/gemini review` on the PR
- Enforce a strict 2-push budget (Push #1 when opening the draft PR, Push #2 after all local `[Style Maintenance]`, `[Independent review follow-ups]`, and local `[Address CI errors]` commits are complete) so GitHub Actions unit tests do not reach their quota
- Run 1 final `/gemini review` on the PR at the very end to confirm no outstanding major issues remain

…apis#9546)

## Description

Adds an opt-in `/passci` agent skill under `.agents/skills/passci/` that
guides coding agents to open a draft pull request immediately after
solving a task (**Push #1 of 2**), create local `[Style Maintenance]`,
`[Independent review follow-ups]`, and `[Address CI errors]` commits,
push all follow-up commits in a single batch (**Push #2 of 2**) to
preserve GitHub Actions quota, and run 1 final `"/gemini review"` on the
PR to confirm no major issues remain.

## Impact

Ensures that pull requests created with `/passci` surface the initial
solution in a draft PR right away while systematically enforcing
repository style guidelines, two independent Gemini reviews per round
within Jetski (up to 5 rounds or until no high-priority issues come up),
and 95% unit test confidence (including packages skipped by conditional
CI triggers) while requiring only 2 `git push` invocations so GitHub
unit tests do not reach their quota.

## Changes

- Added `.agents/skills/passci/SKILL.md` defining the 5-stage opt-in
`/passci` workflow with a strict 2-push budget:
  1. Produce the requested code change on a dedicated branch.
2. **Push #1 of 2**: Open a draft pull request immediately so the
developer can view the suggested changes before follow-up commits are
added.
3. Reference existing contributing guidelines and coding style
documentation (`CONTRIBUTING.md`, `core/packages/gax/CONTRIBUTING.md`,
the Google TypeScript and JavaScript Style Guides, `gts`,
`.eslintrc.json`, `.prettierrc.cjs`, and `bin/linter.mjs`) and create
local style commits prefixed with `[Style Maintenance]`.
4. Conduct **2 independent Gemini code reviews per round locally within
Jetski** (using context-isolated subagents) and create local fixes
prefixed with `[Independent review follow-ups]` up to five times or
until no high-priority issues come up, whatever comes first.
5. Verify unit tests pass locally with at least 95% confidence (even
when skipped by `ci/run_conditional_tests.sh`), resolve any local
CI/test failures with commits prefixed with `[Address CI errors]`,
perform **Push #2 of 2** to push all follow-up commits in a single
batch, and run **1 final `"/gemini review"`** on the PR to confirm no
outstanding major issues remain.
- Added `.agents/skills/passci/scripts/passci.py` to deterministically
audit `CONTRIBUTING.md` style compliance, evaluate independent Gemini
review rounds for high-priority issues, enforce the 2-push budget,
identify CI blind spots, compute 95% confidence unit test plans, and
validate commit prefix ordering.

## Testing

- Verified `passci.py` unit tests covering 95% confidence sample size
calculation ($n = 59$), independent Gemini review stopping conditions (5
rounds max or 0 high-priority issues), CI blind spot classification,
`CONTRIBUTING.md` style auditing, and commit prefix ordering.
- Verified `.agents/skills/passci/scripts/passci.py --repo-root . --mode
audit` against the `google-cloud-node` repository.

## Alternatives

- Running `/gemini review` on the PR and pushing after every
intermediate commit was considered, but conducting the iterative
independent Gemini reviews locally within Jetski (2 reviewers per round,
up to 5 rounds) and batching all follow-up commits into a single second
push avoids exhausting GitHub Actions unit test quota while still
running 1 final `/gemini review` on the PR to confirm no major issues
remain.
- Not merging this PR would leave agents without a standardized opt-in
`/passci` workflow in `googleapis/google-cloud-node`.