Add Qdrant REST support to vector-db SDK

[mySebbe]

Summary

• adds a Qdrant REST wrapper under @arakoodev/edgechains.js/vector-db
• supports collection creation, point upsert/insert, vector search, query, point retrieval, and deletes
• uses direct fetch calls against Qdrant REST endpoints with optional api-key header
• exports Qdrant types/classes from the existing vector-db package entrypoint
• documents basic create/upsert/search usage in the package README

No Qdrant package dependency was added.

Verification

• if (Test-Path dist) { Remove-Item -Recurse -Force dist }; npx tsc -b
• npx jest src/vector-db/src/tests/qdrant/qdrant.test.ts --runInBand
• git diff --check
• npm pack --dry-run

Note: Jest emits existing project config warnings about presets and ts-jest NodeNext settings, but the Qdrant test suite passes.

Fixes #273

/claim #273

[github-actions]

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[mySebbe]

I have read the Arakoo CLA Document and I hereby sign the CLA

[mySebbe]

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