Add Qdrant vector database client

[FlyawayDL]

Add Qdrant vector database client

Closes #273.
/claim #273

Summary

• Adds a Qdrant vector database client implemented against Qdrant's REST API directly.
• Exports Qdrant from @arakoodev/edgechains.js/vector-db.
• Adds mocked tests for point upsert, vector search, and error handling.

Verification

npx tsc -b
npx jest src/vector-db/src/tests/qdrant/qdrant.test.ts --config jest.config.cjs
npx jest src/vector-db/src/tests --config jest.config.cjs

The vector-db test suite passed locally: 7 suites, 10 tests.

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[FlyawayDL]

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