refactor(decision_manager): I2 DI 化 MCP Providers + fix config list type bug

- DecisionManager.__init__ 注入 SSHProvider/K8sProvider，移除函數內 import+實例化
- config.get_tg_user_whitelist() 支援 list 輸入（monkeypatch/直接傳入），修復 AttributeError
- LOGBOOK 更新（test fix 6e0ee8b）

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

apps/api/src/services/decision_manager.py

@@ -1032,6 +1032,12 @@ class DecisionManager:
         # 2026-04-04 Claude Code
         from src.services.knowledge_service import get_knowledge_service
         self._knowledge_svc = get_knowledge_service()
+        # I2 續修 2026-04-12 Claude Sonnet 4.6 Asia/Taipei: 注入 MCP Providers
+        # 原 _collect_mcp_context 在函數內 import + 直接實例化，違反積木化鐵律
+        from src.plugins.mcp.providers.ssh_provider import SSHProvider
+        from src.plugins.mcp.providers.k8s_provider import K8sProvider
+        self._ssh = SSHProvider()
+        self._k8s = K8sProvider()
 
     async def get_or_create_decision(
         self,
@@ -1419,8 +1425,7 @@ class DecisionManager:
         _HOST_ALERT_PREFIXES = ("Host", "Docker", "Sentry", "Harbor", "Ollama", "Backup")
         if alertname.startswith(_HOST_ALERT_PREFIXES) and host:
             try:
-                from src.plugins.mcp.providers.ssh_provider import SSHProvider
-                ssh = SSHProvider()
+                ssh = self._ssh
                 # C4: 未知主機記錄 warning（不靜默跳過）
                 _KNOWN_HOSTS = ("192.168.0.188", "192.168.0.110")
                 if ssh.enabled and host not in _KNOWN_HOSTS:
@@ -1456,8 +1461,7 @@ class DecisionManager:
         # K8s 告警 → K8s MCP 查 Pod 狀態
         if alertname.startswith(("Kube", "K3s")) or labels.get("pod"):
             try:
-                from src.plugins.mcp.providers.k8s_provider import K8sProvider
-                k8s = K8sProvider()
+                k8s = self._k8s
                 if k8s.enabled:
                     pod = labels.get("pod", "")
                     if pod: