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/react-state-management.mdc

@@ -0,0 +1,81 @@
+---
+description: 
+globs: 
+alwaysApply: false
+---
+# React State Management
+
+## Recoil Patterns
+```typescript
+// ✅ Atoms for primitive state
+export const currentUserState = atom<User | null>({
+  key: 'currentUserState',
+  default: null,
+});
+
+// ✅ Selectors for derived state
+export const userDisplayNameSelector = selector({
+  key: 'userDisplayNameSelector',
+  get: ({ get }) => {
+    const user = get(currentUserState);
+    return user ? `${user.firstName} ${user.lastName}` : 'Guest';
+  },
+});
+
+// ✅ Atom families for dynamic atoms
+export const userByIdState = atomFamily<User | null, string>({
+  key: 'userByIdState',
+  default: null,
+});
+```
+
+## Local State Guidelines
+```typescript
+// ✅ Multiple useState for unrelated state
+const [isLoading, setIsLoading] = useState(false);
+const [error, setError] = useState<string | null>(null);
+const [data, setData] = useState<User[]>([]);
+
+// ✅ useReducer for complex state logic
+type FormAction = 
+  | { type: 'SET_FIELD'; field: string; value: string }
+  | { type: 'SET_ERRORS'; errors: Record<string, string> }
+  | { type: 'RESET' };
+
+const formReducer = (state: FormState, action: FormAction): FormState => {
+  switch (action.type) {
+    case 'SET_FIELD':
+      return { ...state, [action.field]: action.value };
+    case 'SET_ERRORS':
+      return { ...state, errors: action.errors };
+    case 'RESET':
+      return initialFormState;
+    default:
+      return state;
+  }
+};
+```
+
+## Data Flow Rules
+- **Props down, events up** - Unidirectional data flow
+- **Avoid bidirectional binding** - Use callback functions
+- **Normalize complex data** - Use lookup tables over nested objects
+
+```typescript
+// ✅ Normalized state structure
+type UsersState = {
+  byId: Record<string, User>;
+  allIds: string[];
+};
+
+// ✅ Functional state updates
+const increment = useCallback(() => {
+  setCount(prev => prev + 1);
+}, []);
+```
+
+## Performance Tips
+- Use atom families for dynamic data collections
+- Implement proper selector caching
+- Avoid heavy computations in selectors
+- Batch state updates when possible