Migrate cursor rules (#12646)

Migrating rules to new format but they should be re-written entirely, I
don't think they help much and are not auto-included (except
architecture)

.cursor/rules/architecture.mdc

@@ -0,0 +1,35 @@
+---
+description: 
+globs: 
+alwaysApply: false
+---
+---
+description: Twenty CRM architecture overview - monorepo structure, tech stack, and development principles
+globs: []
+alwaysApply: true
+---
+
+# Twenty Architecture
+
+## Tech Stack
+- **Frontend**: React 18, TypeScript, Recoil, Styled Components, Vite
+- **Backend**: NestJS, TypeORM, PostgreSQL, Redis, GraphQL
+- **Monorepo**: Nx workspace with yarn
+
+## Package Structure
+```
+packages/
+├── twenty-front/     # React app
+├── twenty-server/    # NestJS API  
+├── twenty-ui/        # Shared components
+├── twenty-shared/    # Common types/utils
+└── twenty-emails/    # Email templates
+```
+
+## Key Principles
+- **Functional components only** (no classes)
+- **Named exports only** (no default exports)
+- **Types over interfaces** (except for extending third-party)
+- **String literals over enums** (except GraphQL)
+- **No 'any' type allowed**
+- **Event handlers over useEffect** for state updates