feat: add Qdrant and PaLM 2 support (#273, #279)

[krysto9872]

What

• Add a dependency-free Qdrant REST client for collection, point, search, scroll, and delete operations.
• Add a typed PaLM 2 generateText adapter with configurable model/version, retries, and injectable HTTP client.
• Export both adapters, add mocked unit coverage, and include a JSONnet-driven PaLM 2 example.

Verification

• npm run build
• npm test -- --run src/ai/src/tests/palm2.test.ts src/vector-db/src/tests/qdrant.test.ts (5 tests passed)
• git diff --check

Fixes arakoodev#273
Fixes arakoodev#279