feat: add hooks and rules

.claude/rules/migrations.md

@@ -0,0 +1,14 @@
+---
+paths:
+  - "**/migrations/**"
+  - "**/*.migration.*"
+  - "**/alembic/**"
+---
+
+# Database Migration Rules
+
+- Every migration must be reversible — include down/rollback logic
+- Never modify existing migrations — create new ones
+- Add indexes for foreign keys and frequently queried columns
+- Use transactions for multi-step migrations
+- Test migrations against a copy of production data when possible