fix(ai): SuggestedAction enum 擴充 + Pydantic fallback 防護

根本原因: NemoTron 輸出 "investigate" → Pydantic 只接受 4 個值 → 爆炸
→ openclaw_analysis_parse_failed → analysis_result=None → 全部 fallback 卡片顯示「待分析」

修復:
1. SuggestedAction enum 新增 INVESTIGATE/OBSERVE/APPLY_HPA/TUNE_RESOURCES
   (prompt.py 列了 6 個，enum 只有 4 個，prompt/model 不同步是根源)
2. normalize_suggested_action validator: uppercase + 別名映射 + 未知值 fallback NO_ACTION
   確保任何 LLM 輸出都不會讓 Pydantic 爆炸導致 analysis_result = None

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

apps/api/src/models/ai.py

@@ -19,11 +19,19 @@ class SuggestedAction(str, Enum):
     AI 建議操作類型
 
     必須與 executor.OperationType 對應
+
+    2026-04-17 ogt + Claude Sonnet 4.6: 新增 INVESTIGATE/APPLY_HPA/TUNE_RESOURCES
+    根本原因: prompts.py 列了 6 個值，但 enum 只有 4 個
+    → NemoTron 輸出 "investigate" → Pydantic 爆炸 → analysis_result = None → 全部 fallback
     """
     RESTART_DEPLOYMENT = "RESTART_DEPLOYMENT"
     DELETE_POD = "DELETE_POD"
     SCALE_DEPLOYMENT = "SCALE_DEPLOYMENT"
-    NO_ACTION = "NO_ACTION"  # 無需處理
+    APPLY_HPA = "APPLY_HPA"
+    TUNE_RESOURCES = "TUNE_RESOURCES"
+    INVESTIGATE = "INVESTIGATE"   # 調查診斷，不下執行指令
+    OBSERVE = "OBSERVE"           # 觀察等待
+    NO_ACTION = "NO_ACTION"       # 無需處理
 
 
 class AIRiskLevel(str, Enum):
@@ -86,6 +94,7 @@ class OpenClawDecision(BaseModel):
         ...,
         description="建議執行的操作類型",
     )
+
     target_resource: str = Field(
         ...,
         description="目標資源名稱 (e.g., 'harbor', 'grafana')",
@@ -192,9 +201,31 @@ class OpenClawDecision(BaseModel):
     @field_validator("suggested_action", mode="before")
     @classmethod
     def normalize_suggested_action(cls, v):
-        """正規化 suggested_action"""
+        """
+        正規化 suggested_action：大小寫 + 別名映射 + 未知值 fallback
+
+        2026-04-17 ogt + Claude Sonnet 4.6（亞太）:
+        根本原因: NemoTron 輸出 "investigate"(小寫) → Pydantic 拒絕 → analysis_result = None
+        舊版只做 uppercase，未知值仍爆 → 修復為: 先 uppercase，再別名映射，最後 fallback NO_ACTION
+        """
         if isinstance(v, str):
-            return v.upper().replace("-", "_").replace(" ", "_")
+            normalized = v.upper().replace("-", "_").replace(" ", "_")
+            # 別名映射 (LLM 可能輸出非正式名稱)
+            alias_map = {
+                "DIAGNOSE": "INVESTIGATE",
+                "DEBUG": "INVESTIGATE",
+                "MONITOR": "OBSERVE",
+                "WATCH": "OBSERVE",
+                "TUNE": "TUNE_RESOURCES",
+                "HPA": "APPLY_HPA",
+            }
+            normalized = alias_map.get(normalized, normalized)
+            # 未知值 fallback NO_ACTION，絕不讓 Pydantic 爆炸導致 analysis_result = None
+            try:
+                SuggestedAction(normalized)
+                return normalized
+            except ValueError:
+                return "NO_ACTION"
         return v