New endpoints:
- POST /clients/:client/blacklist { worker_id, name?, reason? }
- GET /clients/:client/blacklist → { client, entries }
- DELETE /clients/:client/blacklist/:worker_id → { removed, total }
Bun /search accepts optional `client` field. When present, loads that
client's blacklist and appends `AND worker_id NOT IN (...)` to the
SQL filter. Zero-cost if unused; clean trust-break avoidance when a
client has previously flagged a worker.
Persistence: mcp-server/data/client_blacklists.json, synchronous
writes via Bun.write. Scale target is hundreds of entries per client
tops — JSON is fine until we hit 10K+ per client.
Verified: worker_id 9326 (Carmen Green) blacklisted for AcmeCorp,
same Chicago Electrician search with client=AcmeCorp returns 196
sql_matches vs 197 without — exactly one excluded.
cdd12a1438