docs: merge-bar pipeline runs bazel test + hermetic //tools/lint:check (#245 wrap-up)

[obj-p]

Last remaining piece of #245: docs/local-merge-queue.md still described the pre-Bazel merge bar (swift-format lint --strict --recursive). The bar actually runs bazel test //... and the hermetic bazel run //tools/lint:check (see merge-queue/scripts/bar.swift).

Everything else in #245 already shipped on main:

• 4 lint/format tools pinned as prebuilt Bazel externals (//tools/lint)
• bazel run //tools/lint:{check,format,staged}
• pre-commit hook runs the hermetic :staged target
• Brewfile slimmed to bash/bazelisk/xcodes (no Homebrew lint tools)
• merge bar gates on //tools/lint:check

Docs-only change, no runtime surface.

🤖 Generated with Claude Code

[obj-p]

Review pass (workflow-backed, high effort) on the first commit surfaced 4 findings; resolution:

1. bar.swift on main runs --flaky_test_attempts=3 (contradicts the no-retry policy) — already removed on mergequeue-vz-kit (bar there runs plain bazelisk test //...); not papered over here, flagged to the merge-queue workstream.
2. "Pipeline matches the documented merge bar" was false — the bar also requires the example integration tests, which the VM never runs (examples/ is in .bazelignore). Fixed in the second commit: the doc now states the gap.
3. Remote cache in bar.swift vs the snapshot-only hermeticity claim — cache already dropped on mergequeue-vz-kit (d48d9ed); resolves when that branch lands.
4. Line 13's bar definition ("unit tests plus example integration tests") — kept: that is the bar's definition per AGENTS.md; the pipeline section no longer conflates pipeline with bar.