ci: add dependency-review workflow (#22464)

* ci: add dependency-review workflow

Adds a `QA - Dependency review` workflow that runs
`actions/dependency-review-action` on every PR targeting `main`.

This blocks PRs that introduce a *new* dependency (direct or transitive)
with a known high or critical vulnerability in GitHub's Advisory
Database. It complements rather than duplicates Dependabot: Dependabot
surfaces vulns in already-merged dependencies; dependency-review catches
them at the moment they would be introduced.

It also catches the much narrower case that motivated this PR — a
maintainer-account-hijack publishing a malicious version to npm — only
indirectly: GitHub will not have an advisory entry until the package
has been flagged. The real value here is keeping the much larger class
of "newly introduced dep happens to carry a known CVE" out of the tree.

Configured with:

  - fail-on-severity: high  (block on high/critical only)
  - comment-summary-in-pr: on-failure  (surface diff context to
                                        reviewers when a block fires)

Pinned to v5.0.0 (a1d282b36b6f3519aa1f3fc636f609c47dddb294).

Co-authored-by: Agent <279763771+playpen-agent@users.noreply.github.com>

* Update comment.

---------

Co-authored-by: Agent <279763771+playpen-agent@users.noreply.github.com>

.github/workflows/qa-dependency-review.yml

@@ -0,0 +1,32 @@
+---
+name: QA - Dependency review
+
+# Blocks PRs that introduce a dependency with a known vulnerability above
+# the configured severity threshold. Covers every ecosystem GitHub's
+# Advisory Database supports — for this repo that's npm, Go modules,
+# Python (pip/uv), Cargo, and GitHub Actions.
+
+on:
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  dependency-review:
+    name: dependency-review
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v5
+      - uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0
+        with:
+          # Block PRs that introduce a *new* dependency with a known
+          # high/critical vuln. We don't fail on existing vulns — those are
+          # surfaced separately via Dependabot.
+          fail-on-severity: high
+          # Surface a summary comment on the PR itself, in addition to the
+          # check status, so reviewers can see the diff at a glance.
+          comment-summary-in-pr: on-failure