Stable

Fix: Load sqlite-vec extension in database connection

Enable vector search and embeddings support by loading the sqlite-vec extension
when creating database connections in Smriti. This was blocking smriti embed
command from working.

Changes:
- Import sqlite-vec package in src/db.ts
- Load extension in getDb() function via sqliteVec.load(_db)
- Enables vectors_vec virtual table support
- Unlocks hybrid search and semantic recall capabilities

Related: QMD Architecture Deep Dive learning session stored in Smriti

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>