fix: BUG-009/010/011 — DataMasking, cancel button, SQL casts

BUG-009 (P1): Add frontend DataMasking in saas-relay-client.ts
- Masks ID cards, phones, emails, money, company names before relay
- Unmasks tokens in AI response so user sees original data
- Mirrors Rust DataMasking middleware patterns

BUG-010 (P3): Send button transforms to Stop during streaming
- Shows square icon when isStreaming, calls cancelStream()
- Normal arrow icon when idle, calls handleSend()

BUG-011 (P2): Add ::timestamptz casts for old TEXT timestamp columns
- account/handlers.rs: dashboard stats query
- telemetry/service.rs: reported_at comparisons
- workers/aggregate_usage.rs: usage aggregation query

desktop/src/components/ChatArea.tsx

@@ -10,7 +10,7 @@ import { useConfigStore } from '../store/configStore';
 import { useSaaSStore } from '../store/saasStore';
 import { type UnlistenFn } from '@tauri-apps/api/event';
 import { safeListenEvent } from '../lib/safe-tauri';
-import { Paperclip, ArrowUp, MessageSquare, Download, X, FileText, Image as ImageIcon, Search, ClipboardList } from 'lucide-react';
+import { Paperclip, ArrowUp, MessageSquare, Download, X, FileText, Image as ImageIcon, Search, ClipboardList, Square } from 'lucide-react';
 import { Button, EmptyState, MessageListSkeleton, LoadingDots } from './ui';
 import { ResizableChatLayout } from './ai/ResizableChatLayout';
 import { ArtifactPanel } from './ai/ArtifactPanel';
@@ -56,6 +56,7 @@ export function ChatArea({ compact, onOpenDetail }: { compact?: boolean; onOpenD
     sendMessage: sendToGateway, initStreamListener,
     chatMode, setChatMode, suggestions,
     totalInputTokens, totalOutputTokens,
+    cancelStream,
   } = useChatStore();
   const currentAgent = useConversationStore((s) => s.currentAgent);
   const currentModel = useConversationStore((s) => s.currentModel);
@@ -571,16 +572,28 @@ export function ChatArea({ compact, onOpenDetail }: { compact?: boolean; onOpenD
                     disabled={isStreaming}
                   />
                 )}
-                <Button
-                  variant="primary"
-                  size="sm"
-                  onClick={handleSend}
-                  disabled={isStreaming || (!input.trim() && pendingFiles.length === 0)}
-                  className="w-8 h-8 rounded-full p-0 flex items-center justify-center bg-orange-500 hover:bg-orange-600 text-white disabled:opacity-50"
-                  aria-label="发送消息"
-                >
-                  <ArrowUp className="w-4 h-4 text-white" />
-                </Button>
+                {isStreaming ? (
+                  <Button
+                    variant="primary"
+                    size="sm"
+                    onClick={cancelStream}
+                    className="w-8 h-8 rounded-full p-0 flex items-center justify-center bg-gray-500 hover:bg-gray-600 text-white"
+                    aria-label="停止生成"
+                  >
+                    <Square className="w-3.5 h-3.5 text-white fill-white" />
+                  </Button>
+                ) : (
+                  <Button
+                    variant="primary"
+                    size="sm"
+                    onClick={handleSend}
+                    disabled={!input.trim() && pendingFiles.length === 0}
+                    className="w-8 h-8 rounded-full p-0 flex items-center justify-center bg-orange-500 hover:bg-orange-600 text-white disabled:opacity-50"
+                    aria-label="发送消息"
+                  >
+                    <ArrowUp className="w-4 h-4 text-white" />
+                  </Button>
+                )}
               </div>
             </div>
           </div>