feat(agent): add server entry, complete pipeline, and Brave client tests

[macan88]

Problem

The repository had no server entry point (src/index.ts), leaving the four required HTTP endpoints unimplemented and the Brave/rank/synth logic disconnected from any transport. Additionally, the existing logic files lacked test coverage, making correctness unverifiable.

Solution

Added src/index.ts which bootstraps a Hono server, wires the shared in-memory cache, and implements all four endpoints (GET /health, GET /v1/search, GET /v1/search/news, POST /v1/search/deep) by composing braveSearch → rank → synthesise in sequence. The deep-search endpoint fetches web and news results in parallel then merges before ranking, maximising source diversity. A .env.example documents all required environment variables. Focused unit tests for brave.ts cover the web-result normalisation contract, news-result normalisation, the 429 → BraveRateLimitError error path, and the fast-fail behaviour when BRAVE_API_KEY is absent — all using inline fetch mocks so no real network calls are made.

Testing

• Added src/logic/brave.test.ts with 4 focused cases (web normalisation, news normalisation, rate-limit error, missing-key fast-fail)
• Run with bun test src/logic/brave.test.ts
• Manual smoke test: BRAVE_API_KEY=x OPENAI_API_KEY=y bun run src/index.ts then curl localhost:3000/health

Closes #1

[macan88]

Hi 👋

Just checking in on this PR — the implementation is complete and the branch is clean/ready to merge. Happy to address any feedback if needed!

Thanks!