Add Vitest coverage for erasure lanes, fleet evolution UI, and spread routes.

Cover Path Tracer RS lane hints, Calibrate erasure toggle, fleet role chips, atlas skips panel, and erasure_lanes help copy.

server/web/src/pages/BuilderPage.test.tsx

@@ -684,6 +684,28 @@ describe('BuilderPage', () => {
     preflightSpy.mockRestore();
   });
 
+  it('selects fleet role seeder chip in advanced spread section', async () => {
+    const buildSpy = vi.spyOn(api, 'buildAgent');
+    const user = userEvent.setup();
+    renderBuilder();
+    await screen.findByRole('heading', { level: 2, name: 'Quick Forge' });
+    await user.click(screen.getByRole('button', { name: 'Advanced' }));
+    await screen.findByRole('heading', { level: 2, name: 'Build Miner Installer' });
+
+    const seederChip = screen.getByRole('button', { name: 'Seeder' });
+    expect(seederChip).toHaveAttribute(
+      'title',
+      'LAN staging only — dns_txt/webrtc/do_peer, no RandomX',
+    );
+    await user.click(seederChip);
+    expect(seederChip.className).toMatch(/active/);
+
+    await user.click(screen.getByRole('button', { name: /FORGE INSTALLER/i }));
+    await waitFor(() => expect(buildSpy).toHaveBeenCalled());
+    expect(buildSpy.mock.calls[0][0].fleet_role).toBe('seeder');
+    expect(screen.getByText(/Seeder skips mining/i)).toBeInTheDocument();
+  });
+
   it('clears fusion batch queue after successful batch forge', async () => {
     const user = userEvent.setup();
     vi.spyOn(api, 'buildAgent').mockImplementation(async (_req, file) =>