fix: recover watcher and serialize database writers - #1486

Analyzed 8 changed files (21 symbols). Blast radius: 93 files, 237 symbols.

82 affected test files to run:

• __tests__/adaptive-explore-sizing.test.ts
• __tests__/android-res-exclusion.test.ts
• __tests__/c-fnptr-kernel-sweep.test.ts
• __tests__/c-fnptr-synthesizer.test.ts
• __tests__/celery-dispatch-synthesizer.test.ts
• __tests__/cfml-inheritance-resolution.test.ts
• __tests__/cfml-receiver-inference.test.ts
• __tests__/closure-collection-synthesizer.test.ts
• __tests__/concurrent-locking.test.ts
• __tests__/config-secret-redaction.test.ts
• __tests__/context-ranking.test.ts
• __tests__/daemon-bind-failure.test.ts
• __tests__/db-reopen-on-replace.test.ts
• __tests__/dynamic-boundaries.test.ts
• __tests__/erlang-behaviour-synthesizer.test.ts
• __tests__/explore-blast-radius.test.ts
• __tests__/explore-corroboration-ranking.test.ts
• __tests__/explore-nl-stopword-collision.test.ts
• __tests__/explore-output-budget.test.ts
• __tests__/explore-result-count.test.ts

Report: http://localhost:5173/impact/7a5f325e-64ae-4a4f-98fc-6515b22b83f4