[codex] Add metered resume job search

[leini8891]

Summary

• Adds an authenticated /api/jobs/search-from-resume flow that keeps using withAuthenticatedRoute, request-scoped withAppStore(auth.store), and the current candidateId.
• Integrates Adzuna's official jobs API as the compliant aggregator, builds a resume/preference query, ranks fetched jobs with scoreJobAgainstPreferences, saves the selected matches as candidate-scoped job_postings, and reuses the existing saved-job tracker sync via saveManualJob.
• Adds usage-meter logging for resume job search attempts plus existing AI route boundaries for profile parsing, job scoring, and tailored resume generation.

API / Env

• Provider: Adzuna Jobs API (/jobs/{country}/search/{page}).
• Required to enable: ADZUNA_APP_ID, ADZUNA_APP_KEY.
• Optional: ADZUNA_COUNTRY (default sg), ADZUNA_BASE_URL (default https://api.adzuna.com/v1/api).
• If credentials are blank or missing, resume upload/profile workflows still work and job search returns disabled without calling fetch.

Metering

• Usage events are emitted by apps/web/src/server/services/usage-meter.ts as structured [usage-meter] logs.
• resume_job_search records searchCount=1; resume_job_search_disabled records searchCount=0.
• AI route boundaries record profile_parse, job_score, and tailored_resume_generation with aiCallCount based on whether OpenAI is configured.
• Usage metadata avoids logging the generated query text; it records bounded fields like query length, location presence, requested limit, resume id, and fallback mode.

Validation

• pnpm lint
• pnpm test
• pnpm build
• pnpm lint && pnpm test && pnpm build