Add Vertex AI embeddings + semantic search for Learning Hub
- New: Vector search with pgvector extension (cosine similarity)
- Embeddings: Vertex AI text-embedding-005 (768 dims, HIPAA-eligible)
- 3 search modes: keyword, semantic, hybrid (best of both)
- Auto-generate embeddings on content create/update
- Admin endpoints: /api/admin/learning/embeddings/generate (backfill), /status
- User endpoints: /api/learning/search/semantic, /search/hybrid
- Falls back to OpenAI embeddings if Vertex not configured
- Supports LiteLLM proxy routing
Models tested:
- vertex_ai/text-embedding-005 (768 dims, English+code) ✅
- vertex_ai/gemini-embedding-001 (3072 dims, multilingual) ✅
- vertex_ai/text-multilingual-embedding-002 (768 dims) ✅
ea213d8baf