fix(auto-repair): 修復三個阻礙自動修復的根本原因

1. playbook_rag: Ollama embedding http_client 滾動重啟後 is_closed
   - 新增 _get_http_client() 偵測 is_closed 自動重建
   - singleton get_playbook_rag_service() 加 is_closed 重建判斷

2. telegram: 加入 ai_model 欄位顯示底層判斷模型
   - TelegramMessage.ai_model 欄位
   - format() / format_with_nemotron() 顯示 "Nemotron (nemotron-70b)"
   - openclaw proposal_dict 加入 model 欄位
   - decision_manager / send_approval_card 串接

3. DB: 清除 9 筆 3/26 殭屍 PENDING (mock_fallback CRITICAL 測試記錄)

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

apps/api/src/services/playbook_rag.py

@@ -153,11 +153,24 @@ class PlaybookRAGService:
     # Embedding Operations
     # =========================================================================
 
+    async def _get_http_client(self) -> httpx.AsyncClient:
+        """
+        取得有效的 HTTP Client，若已關閉則重建
+
+        2026-04-04 ogt: 修復滾動重啟後 is_closed=True 導致 embedding 失敗
+        """
+        if self._http_client.is_closed:
+            logger.warning("playbook_rag_http_client_closed_rebuilding")
+            from src.core.http_client import get_general_client
+            self._http_client = await get_general_client()
+        return self._http_client
+
     async def embed_text(self, text: str) -> list[float] | None:
         """
         使用 Ollama 生成文字 embedding
 
         2026-03-27 ogt: 改用 DI 注入的 http_client (P1 違規修復)
+        2026-04-04 ogt: 加入 is_closed 自動重建機制
 
         Args:
             text: 要向量化的文字
@@ -166,8 +179,8 @@ class PlaybookRAGService:
             向量 (768 維) 或 None (失敗時)
         """
         try:
-            # 使用 DI 注入的 http_client，設置單次請求 timeout
-            response = await self._http_client.post(
+            client = await self._get_http_client()
+            response = await client.post(
                 f"{self.ollama_url}/api/embeddings",
                 json={
                     "model": self.embedding_model,
@@ -545,7 +558,8 @@ async def get_playbook_rag_service() -> PlaybookRAGService:
     2026-03-27 ogt: 改用 DI 注入，從 Lifespan 取得 http_client 和 Redis
     """
     global _rag_service
-    if _rag_service is None:
+    # 2026-04-04 ogt: 滾動重啟後 http_client is_closed，需重建 singleton
+    if _rag_service is None or _rag_service._http_client.is_closed:
         # 延遲導入避免循環依賴
         from src.core.http_client import get_general_client
         from src.core.redis_client import get_redis