feat(mp): AI 聊天传递 patient_id 支持体征数据查询 Tool Call

- ai-chat service: sendAiMessage 新增 patientId 可选参数
- messages 页面: 从 authStore 获取 currentPatient.id 传入

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/miniprogram/src/pages/messages/index.tsx

@@ -26,6 +26,7 @@ function genId(): string {
 
 export default function Messages() {
   const user = useAuthStore((s) => s.user);
+  const currentPatient = useAuthStore((s) => s.currentPatient);
   const modeClass = useElderClass();
   const [messages, setMessages] = useState<AiChatMessage[]>([]);
   const [inputText, setInputText] = useState('');
@@ -70,7 +71,7 @@ export default function Messages() {
     scrollToBottom(next);
 
     try {
-      const resp = await sendAiMessage(content, next);
+      const resp = await sendAiMessage(content, next, currentPatient?.id);
       const aiMsg: AiChatMessage = {
         id: resp.message_id || genId(),
         role: 'assistant',