fix: Add embedding column to epics table

Migration 003: enables semantic search for epics
- ALTER TABLE epics ADD COLUMN embedding vector(1024)
- HNSW index for similarity search

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

migrations/003_epics_embedding.sql

@@ -0,0 +1,12 @@
+-- Migration 003: Add embedding column to epics table
+-- Enables semantic search for epics
+
+-- Add embedding column to epics table
+ALTER TABLE epics ADD COLUMN IF NOT EXISTS embedding vector(1024);
+
+-- Create HNSW index for fast vector similarity search
+CREATE INDEX IF NOT EXISTS idx_epics_embedding ON epics USING hnsw (embedding vector_cosine_ops);
+
+-- Record migration
+INSERT INTO schema_migrations (version, applied_at) VALUES ('003_epics_embedding', NOW())
+ON CONFLICT DO NOTHING;