Merge predicted-gate-engine-branch-coverage.test.ts into predicted-gate-engine-coverage.test.ts

[JSONbored]

Part of the '-coverage' bolt-on consolidation epic (#8574 — non-closing reference).

Both files are bolt-ons for the same module and the same original issue (#2283):

• test/unit/predicted-gate-engine-coverage.test.ts (1432 lines, describe("predicted-gate engine module coverage (#2283)"))
• test/unit/predicted-gate-engine-branch-coverage.test.ts (708 lines, describe("predicted-gate engine branch coverage (#2283)"))

Both import evaluateGateCheck / buildPullRequestAdvisory / gateAdvisoryInternals from packages/loopover-engine/src/advisory/gate-advisory and visibly re-exercise the same collision / cla-check / gate-evaluation paths under generic titles ("exercises collision pairwise branch arms", "mirrors engine cla-check and pre-merge-check branches").

Task

• Diff the two files' cases against each other; identify true duplicates (same branch arm exercised) vs unique cases.
• Merge unique cases from -branch-coverage into -coverage, retitling generic names to behavior specs where cheap.
• Delete predicted-gate-engine-branch-coverage.test.ts.
• Verify zero coverage regression on packages/loopover-engine/src/advisory/gate-advisory* with an unsharded npm run test:coverage before/after comparison.

[linear-code]

JSO-5940