feat(ui): add copilot-api install button and version display

- add CopilotInfo type and install mutation to useCopilot hook

- show version in status card when installed

- add Install button with loading state when not installed

ui/src/components/copilot/copilot-status-card.tsx

@@ -8,7 +8,7 @@ import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/com
 import { Badge } from '@/components/ui/badge';
 import { Button } from '@/components/ui/button';
 import { useCopilot } from '@/hooks/use-copilot';
-import { CheckCircle2, XCircle, AlertTriangle, Loader2 } from 'lucide-react';
+import { CheckCircle2, XCircle, AlertTriangle, Loader2, Download } from 'lucide-react';
 
 export function CopilotStatusCard() {
   const {
@@ -20,6 +20,8 @@ export function CopilotStatusCard() {
     isStartingDaemon,
     stopDaemon,
     isStoppingDaemon,
+    install,
+    isInstalling,
   } = useCopilot();
 
   if (statusLoading) {
@@ -80,7 +82,7 @@ export function CopilotStatusCard() {
               <XCircle className="h-5 w-5 text-red-500" />
             )}
             <span className="text-sm">
-              copilot-api {status.installed ? 'Installed' : 'Not Installed'}
+              copilot-api {status.installed ? `v${status.version}` : 'Not Installed'}
             </span>
           </div>
 
@@ -116,6 +118,22 @@ export function CopilotStatusCard() {
 
         {/* Actions */}
         <div className="flex flex-wrap gap-2 pt-2">
+          {!status.installed && (
+            <Button onClick={() => install(undefined)} disabled={isInstalling} size="sm">
+              {isInstalling ? (
+                <>
+                  <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+                  Installing...
+                </>
+              ) : (
+                <>
+                  <Download className="mr-2 h-4 w-4" />
+                  Install copilot-api
+                </>
+              )}
+            </Button>
+          )}
+
           {!status.authenticated && (
             <Button
               onClick={() => startAuth()}

ui/src/hooks/use-copilot.ts

@@ -12,6 +12,7 @@ const API_BASE = '/api';
 export interface CopilotStatus {
   enabled: boolean;
   installed: boolean;
+  version: string | null;
   authenticated: boolean;
   daemon_running: boolean;
   port: number;
@@ -22,6 +23,20 @@ export interface CopilotStatus {
   wait_on_limit: boolean;
 }
 
+export interface CopilotInfo {
+  installed: boolean;
+  version: string | null;
+  path: string;
+  pinnedVersion: string | null;
+}
+
+export interface CopilotInstallResult {
+  success: boolean;
+  installed: boolean;
+  version: string | null;
+  path: string;
+}
+
 export interface CopilotConfig {
   enabled: boolean;
   auto_start: boolean;
@@ -120,6 +135,22 @@ async function stopCopilotDaemon(): Promise<{ success: boolean; error?: string }
   return res.json();
 }
 
+async function fetchCopilotInfo(): Promise<CopilotInfo> {
+  const res = await fetch(`${API_BASE}/copilot/info`);
+  if (!res.ok) throw new Error('Failed to fetch copilot info');
+  return res.json();
+}
+
+async function installCopilotApi(version?: string): Promise<CopilotInstallResult> {
+  const res = await fetch(`${API_BASE}/copilot/install`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(version ? { version } : {}),
+  });
+  if (!res.ok) throw new Error('Failed to install copilot-api');
+  return res.json();
+}
+
 // Hook
 export function useCopilot() {
   const queryClient = useQueryClient();
@@ -146,6 +177,11 @@ export function useCopilot() {
     queryFn: fetchCopilotRawSettings,
   });
 
+  const infoQuery = useQuery({
+    queryKey: ['copilot-info'],
+    queryFn: fetchCopilotInfo,
+  });
+
   // Mutations
   const updateConfigMutation = useMutation({
     mutationFn: updateCopilotConfig,
@@ -189,6 +225,14 @@ export function useCopilot() {
     },
   });
 
+  const installMutation = useMutation({
+    mutationFn: installCopilotApi,
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['copilot-status'] });
+      queryClient.invalidateQueries({ queryKey: ['copilot-info'] });
+    },
+  });
+
   return {
     // Status
     status: statusQuery.data,
@@ -227,5 +271,14 @@ export function useCopilot() {
 
     stopDaemon: stopDaemonMutation.mutate,
     isStoppingDaemon: stopDaemonMutation.isPending,
+
+    // Install
+    info: infoQuery.data,
+    infoLoading: infoQuery.isLoading,
+    refetchInfo: infoQuery.refetch,
+
+    install: installMutation.mutate,
+    installAsync: installMutation.mutateAsync,
+    isInstalling: installMutation.isPending,
   };
 }