chore: update gitignore and restore backend files

- Add backend/node_modules to .gitignore
- Untrack backend/node_modules from git
- Restore backend source files (go.mod, main.go, etc.) that were missing in HEAD
- Include frontend test updates

frontend/src/components/ProxyHostForm.tsx

@@ -88,10 +88,11 @@ export default function ProxyHostForm({ host, onSubmit, onCancel }: ProxyHostFor
           {/* Remote Server Quick Select */}
           {remoteServers.length > 0 && (
             <div>
-              <label className="block text-sm font-medium text-gray-300 mb-2">
+              <label htmlFor="quick-select" className="block text-sm font-medium text-gray-300 mb-2">
                 Quick Select from Remote Servers
               </label>
               <select
+                id="quick-select"
                 onChange={e => handleServerSelect(e.target.value)}
                 className="w-full bg-gray-900 border border-gray-700 rounded-lg px-4 py-2 text-white focus:outline-none focus:ring-2 focus:ring-blue-500"
               >
@@ -212,10 +213,11 @@ export default function ProxyHostForm({ host, onSubmit, onCancel }: ProxyHostFor
 
           {/* Advanced Config */}
           <div>
-            <label className="block text-sm font-medium text-gray-300 mb-2">
+            <label htmlFor="advanced-config" className="block text-sm font-medium text-gray-300 mb-2">
               Advanced Caddy Config (Optional)
             </label>
             <textarea
+              id="advanced-config"
               value={formData.advanced_config}
               onChange={e => setFormData({ ...formData, advanced_config: e.target.value })}
               placeholder="Additional Caddy directives..."

frontend/src/components/__tests__/ProxyHostForm.test.tsx

@@ -149,4 +149,54 @@ describe('ProxyHostForm', () => {
     expect(sslCheckbox).toBeChecked()
     expect(wsCheckbox).toBeChecked()
   })
+
+  it('populates fields when remote server is selected', async () => {
+    renderWithClient(
+      <ProxyHostForm onSubmit={mockOnSubmit} onCancel={mockOnCancel} />
+    )
+
+    await waitFor(() => {
+      expect(screen.getByText(/Local Docker Registry/)).toBeInTheDocument()
+    })
+
+    const select = screen.getByRole('combobox', { name: /quick select/i })
+    fireEvent.change(select, { target: { value: mockRemoteServers[0].uuid } })
+
+    expect(screen.getByDisplayValue(mockRemoteServers[0].host)).toBeInTheDocument()
+    expect(screen.getByDisplayValue(mockRemoteServers[0].port)).toBeInTheDocument()
+  })
+
+  it('displays error message on submission failure', async () => {
+    const mockErrorSubmit = vi.fn(() => Promise.reject(new Error('Submission failed')))
+    renderWithClient(
+      <ProxyHostForm onSubmit={mockErrorSubmit} onCancel={mockOnCancel} />
+    )
+
+    fireEvent.change(screen.getByPlaceholderText('example.com, www.example.com'), {
+      target: { value: 'test.com' },
+    })
+    fireEvent.change(screen.getByPlaceholderText('192.168.1.100'), {
+      target: { value: 'localhost' },
+    })
+    fireEvent.change(screen.getByDisplayValue('80'), {
+      target: { value: '8080' },
+    })
+
+    fireEvent.click(screen.getByText('Create'))
+
+    await waitFor(() => {
+      expect(screen.getByText('Submission failed')).toBeInTheDocument()
+    })
+  })
+
+  it('handles advanced config input', async () => {
+    renderWithClient(
+      <ProxyHostForm onSubmit={mockOnSubmit} onCancel={mockOnCancel} />
+    )
+
+    const advancedInput = screen.getByLabelText(/Advanced Caddy Config/i)
+    fireEvent.change(advancedInput, { target: { value: 'header_up X-Test "True"' } })
+
+    expect(advancedInput).toHaveValue('header_up X-Test "True"')
+  })
 })

frontend/src/pages/__tests__/Setup.test.tsx

@@ -1,10 +1,20 @@
-import { render, screen, waitFor } from '@testing-library/react';
+import { render, screen, waitFor, fireEvent } from '@testing-library/react';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
 import { MemoryRouter } from 'react-router-dom';
 import { vi, describe, it, expect, beforeEach } from 'vitest';
 import Setup from '../Setup';
 import * as setupApi from '../../api/setup';
 
+// Mock react-router-dom
+const mockNavigate = vi.fn();
+vi.mock('react-router-dom', async () => {
+  const actual = await vi.importActual('react-router-dom');
+  return {
+    ...actual,
+    useNavigate: () => mockNavigate,
+  };
+});
+
 // Mock the API module
 vi.mock('../../api/setup', () => ({
   getSetupStatus: vi.fn(),
@@ -57,5 +67,61 @@ describe('Setup Page', () => {
     await waitFor(() => {
       expect(screen.queryByText('Welcome to CPM+')).toBeNull();
     });
+
+    await waitFor(() => {
+      expect(mockNavigate).toHaveBeenCalledWith('/login');
+    });
+  });
+
+  it('submits form successfully', async () => {
+    vi.mocked(setupApi.getSetupStatus).mockResolvedValue({ setupRequired: true });
+    vi.mocked(setupApi.performSetup).mockResolvedValue();
+
+    renderWithProviders(<Setup />);
+
+    await waitFor(() => {
+      expect(screen.getByText('Welcome to CPM+')).toBeTruthy();
+    });
+
+    fireEvent.change(screen.getByLabelText('Name'), { target: { value: 'Admin' } });
+    fireEvent.change(screen.getByLabelText('Email Address'), { target: { value: 'admin@example.com' } });
+    fireEvent.change(screen.getByLabelText('Password'), { target: { value: 'password123' } });
+
+    fireEvent.click(screen.getByRole('button', { name: 'Create Admin Account' }));
+
+    await waitFor(() => {
+      expect(setupApi.performSetup).toHaveBeenCalledWith({
+        name: 'Admin',
+        email: 'admin@example.com',
+        password: 'password123',
+      }, expect.anything());
+    });
+
+    await waitFor(() => {
+      expect(mockNavigate).toHaveBeenCalledWith('/login');
+    });
+  });
+
+  it('displays error on submission failure', async () => {
+    vi.mocked(setupApi.getSetupStatus).mockResolvedValue({ setupRequired: true });
+    vi.mocked(setupApi.performSetup).mockRejectedValue({
+      response: { data: { error: 'Setup failed' } }
+    });
+
+    renderWithProviders(<Setup />);
+
+    await waitFor(() => {
+      expect(screen.getByText('Welcome to CPM+')).toBeTruthy();
+    });
+
+    fireEvent.change(screen.getByLabelText('Name'), { target: { value: 'Admin' } });
+    fireEvent.change(screen.getByLabelText('Email Address'), { target: { value: 'admin@example.com' } });
+    fireEvent.change(screen.getByLabelText('Password'), { target: { value: 'password123' } });
+
+    fireEvent.click(screen.getByRole('button', { name: 'Create Admin Account' }));
+
+    await waitFor(() => {
+      expect(screen.getByText('Setup failed')).toBeTruthy();
+    });
   });
 });