feat: add AGENTS.md for all packages and apps (9 files)

packages/api/AGENTS.md

@@ -0,0 +1,17 @@
+# @repo/api — tRPC Router Definitions
+
+tRPC routers that call controllers from `@repo/core`. Each procedure validates input and delegates to a controller.
+
+## Rules
+
+- NEVER put business logic in routers — delegate to controllers
+- Input validation uses Zod schemas
+- Each domain gets its own router file
+
+## Adding a New tRPC Router
+
+1. Create `src/router/{domain}.router.ts`
+2. Import `router` and `publicProcedure` from `../trpc.js`
+3. Define procedures (`.query()` for reads, `.mutation()` for writes)
+4. Each procedure calls a controller from `@repo/core`
+5. Add router to root `appRouter` in `src/router/index.ts`