feat: production readiness improvements

## Error Handling
- Add GlobalErrorBoundary with error classification and recovery
- Add custom error types (SecurityError, ConnectionError, TimeoutError)
- Fix ErrorAlert component syntax errors

## Offline Mode
- Add offlineStore for offline state management
- Implement message queue with localStorage persistence
- Add exponential backoff reconnection (1s→60s)
- Add OfflineIndicator component with status display
- Queue messages when offline, auto-retry on reconnect

## Security Hardening
- Add AES-256-GCM encryption for chat history storage
- Add secure API key storage with OS keychain integration
- Add security audit logging system
- Add XSS prevention and input validation utilities
- Add rate limiting and token generation helpers

## CI/CD (Gitea Actions)
- Add .gitea/workflows/ci.yml for continuous integration
- Add .gitea/workflows/release.yml for release automation
- Support Windows Tauri build and release

## UI Components
- Add LoadingSpinner, LoadingOverlay, LoadingDots components
- Add MessageSkeleton, ConversationListSkeleton skeletons
- Add EmptyMessages, EmptyConversations empty states
- Integrate loading states in ChatArea and ConversationList

## E2E Tests
- Fix WebSocket mock for streaming response tests
- Fix approval endpoint route matching
- Add store state exposure for testing
- All 19 core-features tests now passing

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

desktop/src/components/ui/Skeleton.tsx

@@ -40,3 +40,142 @@ export function ListSkeleton({ count = 3 }: { count?: number }) {
     </div>
   );
 }
+
+/**
+ * Skeleton for a single chat message bubble.
+ * Supports both user and assistant message styles.
+ */
+export function MessageSkeleton({ isUser = false }: { isUser?: boolean }) {
+  return (
+    <div className={cn('flex gap-4', isUser && 'justify-end')}>
+      <div
+        className={cn(
+          'w-8 h-8 rounded-lg flex-shrink-0',
+          isUser ? 'bg-gray-200 dark:bg-gray-600 order-last' : 'bg-gray-300 dark:bg-gray-600'
+        )}
+      >
+        <Skeleton className="w-full h-full rounded-lg" />
+      </div>
+      <div className={cn('flex-1', isUser && 'max-w-2xl')}>
+        <div
+          className={cn(
+            'p-4 rounded-2xl',
+            isUser
+              ? 'bg-orange-100 dark:bg-orange-900/30'
+              : 'bg-gray-50 dark:bg-gray-800 border border-gray-200 dark:border-gray-700'
+          )}
+        >
+          <Skeleton className="h-4 w-full mb-2" />
+          <Skeleton className="h-4 w-3/4 mb-2" />
+          <Skeleton className="h-4 w-1/2" />
+        </div>
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Skeleton for a list of chat messages.
+ * Alternates between user and assistant skeletons.
+ */
+export function MessageListSkeleton({ count = 4 }: { count?: number }) {
+  return (
+    <div className="space-y-6 p-6">
+      {Array.from({ length: count }).map((_, i) => (
+        <MessageSkeleton key={i} isUser={i % 2 === 0} />
+      ))}
+    </div>
+  );
+}
+
+/**
+ * Skeleton for a conversation item in the sidebar.
+ */
+export function ConversationItemSkeleton() {
+  return (
+    <div className="flex items-center gap-3 px-3 py-3 border-b border-gray-50 dark:border-gray-800">
+      <Skeleton className="w-7 h-7 rounded-lg flex-shrink-0" />
+      <div className="flex-1 min-w-0">
+        <Skeleton className="h-3 w-24 mb-1.5" />
+        <Skeleton className="h-2 w-32" />
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Skeleton for the conversation list sidebar.
+ */
+export function ConversationListSkeleton({ count = 5 }: { count?: number }) {
+  return (
+    <div className="flex flex-col h-full">
+      {/* Header skeleton */}
+      <div className="flex items-center justify-between px-3 py-2 border-b border-gray-200 dark:border-gray-700">
+        <Skeleton className="h-3 w-16" />
+        <Skeleton className="w-4 h-4 rounded" />
+      </div>
+      {/* List items */}
+      <div className="flex-1 overflow-hidden">
+        {Array.from({ length: count }).map((_, i) => (
+          <ConversationItemSkeleton key={i} />
+        ))}
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Skeleton for the chat header.
+ */
+export function ChatHeaderSkeleton() {
+  return (
+    <div className="h-14 border-b border-gray-100 dark:border-gray-800 flex items-center justify-between px-6 bg-white dark:bg-gray-900">
+      <div className="flex items-center gap-2">
+        <Skeleton className="h-5 w-24" />
+        <Skeleton className="h-3 w-20" />
+      </div>
+      <div className="flex items-center gap-2">
+        <Skeleton className="h-8 w-8 rounded-full" />
+        <Skeleton className="h-8 w-8 rounded-full" />
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Skeleton for the chat input area.
+ */
+export function ChatInputSkeleton() {
+  return (
+    <div className="border-t border-gray-100 dark:border-gray-800 p-4 bg-white dark:bg-gray-900">
+      <div className="max-w-4xl mx-auto">
+        <div className="flex items-end gap-2 bg-gray-50 dark:bg-gray-800 rounded-2xl border border-gray-200 dark:border-gray-700 p-2">
+          <Skeleton className="w-5 h-5 rounded" />
+          <div className="flex-1 py-1">
+            <Skeleton className="h-5 w-full" />
+          </div>
+          <Skeleton className="w-16 h-6 rounded" />
+          <Skeleton className="w-8 h-8 rounded-full" />
+        </div>
+        <div className="text-center mt-2">
+          <Skeleton className="h-3 w-40 mx-auto" />
+        </div>
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Full chat area skeleton including header, messages, and input.
+ */
+export function ChatAreaSkeleton({ messageCount = 4 }: { messageCount?: number }) {
+  return (
+    <div className="flex flex-col h-full">
+      <ChatHeaderSkeleton />
+      <div className="flex-1 overflow-hidden">
+        <MessageListSkeleton count={messageCount} />
+      </div>
+      <ChatInputSkeleton />
+    </div>
+  );
+}