Add app update detection and multi-folder project support

Feature 1 - Update Detection: Query Gitea releases API on startup (3s
delay) and every 24h, compare patch versions by platform, show pulsing
"Update" button in TopBar with dialog for release notes/downloads.
Settings: auto-check toggle, manual check, dismiss per-version.

Feature 2 - Multi-Folder Projects: Replace single `path` with
`paths: Vec<ProjectPath>` (host_path + mount_name). Each folder mounts
to `/workspace/{mount_name}`. Auto-migrate old single-path JSON on load.
Container recreation via paths-fingerprint label. AddProjectDialog and
ProjectCard support add/remove/edit of multiple folders.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/components/settings/SettingsPanel.tsx

@@ -3,10 +3,13 @@ import ApiKeyInput from "./ApiKeyInput";
 import DockerSettings from "./DockerSettings";
 import AwsSettings from "./AwsSettings";
 import { useSettings } from "../../hooks/useSettings";
+import { useUpdates } from "../../hooks/useUpdates";
 
 export default function SettingsPanel() {
   const { appSettings, saveSettings } = useSettings();
+  const { appVersion, checkForUpdates } = useUpdates();
   const [globalInstructions, setGlobalInstructions] = useState(appSettings?.global_claude_instructions ?? "");
+  const [checkingUpdates, setCheckingUpdates] = useState(false);
 
   // Sync local state when appSettings change
   useEffect(() => {
@@ -18,6 +21,20 @@ export default function SettingsPanel() {
     await saveSettings({ ...appSettings, global_claude_instructions: globalInstructions || null });
   };
 
+  const handleCheckNow = async () => {
+    setCheckingUpdates(true);
+    try {
+      await checkForUpdates();
+    } finally {
+      setCheckingUpdates(false);
+    }
+  };
+
+  const handleAutoCheckToggle = async () => {
+    if (!appSettings) return;
+    await saveSettings({ ...appSettings, auto_check_updates: !appSettings.auto_check_updates });
+  };
+
   return (
     <div className="p-4 space-y-6">
       <h2 className="text-xs font-semibold uppercase text-[var(--text-secondary)]">
@@ -40,6 +57,38 @@ export default function SettingsPanel() {
           className="w-full px-2 py-1.5 text-xs bg-[var(--bg-primary)] border border-[var(--border-color)] rounded focus:outline-none focus:border-[var(--accent)] resize-y font-mono"
         />
       </div>
+
+      {/* Updates section */}
+      <div>
+        <label className="block text-sm font-medium mb-2">Updates</label>
+        <div className="space-y-2">
+          {appVersion && (
+            <p className="text-xs text-[var(--text-secondary)]">
+              Current version: <span className="text-[var(--text-primary)] font-mono">{appVersion}</span>
+            </p>
+          )}
+          <div className="flex items-center gap-2">
+            <label className="text-xs text-[var(--text-secondary)]">Auto-check for updates</label>
+            <button
+              onClick={handleAutoCheckToggle}
+              className={`px-2 py-0.5 text-xs rounded transition-colors ${
+                appSettings?.auto_check_updates !== false
+                  ? "bg-[var(--success)] text-white"
+                  : "bg-[var(--bg-primary)] border border-[var(--border-color)] text-[var(--text-secondary)]"
+              }`}
+            >
+              {appSettings?.auto_check_updates !== false ? "ON" : "OFF"}
+            </button>
+          </div>
+          <button
+            onClick={handleCheckNow}
+            disabled={checkingUpdates}
+            className="px-3 py-1.5 text-xs bg-[var(--bg-primary)] border border-[var(--border-color)] rounded hover:bg-[var(--border-color)] disabled:opacity-50 transition-colors"
+          >
+            {checkingUpdates ? "Checking..." : "Check now"}
+          </button>
+        </div>
+      </div>
     </div>
   );
 }