fix(migrations): use exact smartdata collection names in route unification migration

AGENTS.md

@@ -0,0 +1,17 @@
+# Agent Instructions for dcrouter
+
+## Database & Migrations
+
+### Collection Names
+smartdata uses the **exact class name** as the MongoDB collection name. No lowercasing.
+- `StoredRouteDoc` → collection `StoredRouteDoc`
+- `TargetProfileDoc` → collection `TargetProfileDoc`
+- `RouteDoc` → collection `RouteDoc`
+
+When writing migrations in `ts_migrations/index.ts`, use the exact class name casing in `ctx.mongo!.collection('ClassName')` and `db.listCollections({ name: 'ClassName' })`.
+
+### Migration Rules
+- All DB schema migrations go EXCLUSIVELY in `ts_migrations/index.ts` as smartmigration steps.
+- NEVER put migration logic in application code (services, managers, startup hooks).
+- Migration step `.to()` version must match the release version so smartmigration can plan the step.
+- Steps must be idempotent — smartmigration may re-run them in skip-forward resume mode.