perf(source-control): skip ready's local full-suite verify when the CI test lanes cover it #8753

Refs: #3716

Problem

/source-control:pull-request ready runs the verify gate locally on the merged head before flipping the PR. On #8714 that run took about 27 minutes: scripts/check-affected.sh --tests selected about 140 *.test.sh suites, and one of them failed until the run did an npm ci. CI then ran the same suites in about 8 minutes (pr-require-checks, measured on the branch's runs). The local run bought nothing CI did not also check, and it was the largest single delay between PR creation and merge.

Fix

When the CI test lanes are present and healthy for the change (the same venue check review-venue already does for the AI review lanes), ready skips the local full-suite verify. It runs locally only what CI cannot, and says which suites it skipped. ready --verify-local keeps the current behavior on request.

"Healthy for the change" means: a successful test-lane run (pr-require-checks test jobs) exists at the merged head SHA. A draft has none ("A draft skips the test lanes", AGENTS.md), so the local verify runs as today. ci-status still gates the merge either way.

Verification

A ready run on a PR whose CI lanes are healthy reports the verify step as skipped (CI covers it) and flips the PR in minutes.

Split to #8994: that live ready run, observed after this merges.

Done when (lane)

• plugins/source-control/skills/pull-request/scripts/review-venue.sh reports a test-lane row: ci when a successful test-lane run exists at the given head, otherwise local. Check: the PR's CI runs review-venue.test.sh with a fixture for each state, and it passes.
• plugins/source-control/skills/pull-request/reference/ready-for-review.md (the verify step at :204) skips check-affected.sh --tests when that row is ci, records --result skipped through verify-gate.sh, reports skipped (CI covers it) and names the skipped suites; it runs the suites when the row is local or with --verify-local. Check: the PR's CI runs verify-gate.test.sh and the markdown lint, and they pass.
• The --verify-local flag and the skip line exist in the skill text. Check: the PR's CI runs a skill-text test for both strings (new or extended *.test.sh in that skill), and it passes.
• A .changes/source-control/ fragment exists. Check: the PR's CI runs scripts/check-changelog-fragments.sh --check and it passes.
• Out of scope: AGENTS.md (its wording still holds).

Related

#8714, #3716, #3932