DB-003: Add ./embeddings subpath export to root package.json

[sparkling]

Root package.json missing ./embeddings export causing import failure. Fix: commit ee77e40. Refs: ADR-0031 BUG-4.

[ruvnet]

Fixed in #133 (PR from branch fix/update-deps-and-cleanup)

Added ./embeddings subpath export to root package.json exports:

"./embeddings": "./agentic-flow/dist/agentdb/services/embeddings.js"

Verified working in v3.0.0-alpha.2.