chore: add pre-commit hooks, tighten ESLint, activate Sentry DSN, publish CI coverage (Phase 1)

- Install husky v9 + lint-staged: pre-commit runs eslint --fix and prettier on staged files
- Tighten ESLint base config: no-console→error, ban-ts-comment (ts-ignore banned, ts-expect-error with description allowed), reportUnusedDisableDirectives→error
- Migrate web app from deprecated `next lint` to `eslint src/` with flat config and react-hooks plugin
- Convert all 5 @ts-ignore to @ts-expect-error with descriptions, remove stale disable comments
- Add NEXT_PUBLIC_SENTRY_DSN to docker-compose.prod.yml and .env.example
- Add coverage artifact upload step to CI test job
- Pre-existing violations (102 warnings) downgraded to warn in web config for Phase 2 cleanup

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.prod.yml

@@ -70,6 +70,7 @@ services:
       DATABASE_URL: postgresql://capakraken:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD}@postgres:5432/capakraken
       REDIS_URL: redis://:${REDIS_PASSWORD}@redis:6379
       RATE_LIMIT_BACKEND: ${RATE_LIMIT_BACKEND:-redis}
+      NEXT_PUBLIC_SENTRY_DSN: ${NEXT_PUBLIC_SENTRY_DSN:-}
     depends_on:
       postgres:
         condition: service_healthy