feat: employee management — add/delete users from Members page

- Backend: POST /api/auth/users (create user), DELETE /api/auth/users/:id (delete user, unassign tasks)
- Frontend API: apiCreateUser, apiDeleteUser
- MembersPage: working Add Employee modal (name/email/password/role/dept), delete button with confirmation
- Only CEO/CTO/Manager roles see management controls
- CSS: btn-danger, btn-danger-sm styles

src/api.ts

@@ -33,6 +33,21 @@ export async function apiFetchUsers() {
     return request('/auth/users');
 }
 
+export async function apiCreateUser(data: {
+    name: string; email: string; password: string; role?: string; dept?: string;
+}) {
+    return request('/auth/users', {
+        method: 'POST',
+        body: JSON.stringify(data),
+    });
+}
+
+export async function apiDeleteUser(id: string) {
+    return request(`/auth/users/${id}`, {
+        method: 'DELETE',
+    });
+}
+
 // Tasks
 export async function apiFetchTasks() {
     return request('/tasks');