feat: admin user management (create/search/role) and cluster resource monitoring

- Add POST /users endpoint for admin to create users with hashed passwords
- Add GET /users?search= with ILike search on email/firstName/lastName
- Add PATCH /users/:id/role for role assignment (user/admin)
- Return appCount per user in the users list
- Add GET /clusters/:id/resources for node, CPU, memory, pod monitoring
- Parse K8s node capacity/allocatable with CPU millicores and memory MiB helpers
- Frontend: admin users page with search bar, create form, role dropdown, app count
- Frontend: cluster resource panel with nodes table, CPU/memory bars, summary cards

backend/src/clusters/clusters.controller.ts

@@ -54,6 +54,13 @@ export class ClustersController {
     return this.clustersService.findAll();
   }
 
+  @Get(':id/resources')
+  @Roles(UserRole.ADMIN)
+  @ApiOperation({ summary: 'Get cluster resource usage — nodes, CPU, memory, pods (Admin only)' })
+  async getClusterResources(@Param('id') id: string) {
+    return this.clustersService.getClusterResources(id);
+  }
+
   @Get(':id')
   @Roles(UserRole.ADMIN)
   @ApiOperation({ summary: 'Get cluster details (Admin only)' })