fix(sprint3): 首席架構師 Review C1/C2/C3/M3/m1 修正

C1: _ssh_execute 直接接收 key_path 參數，不反查 LAYER_SSH_CONFIG
C2: PlaybookService.create() proxy，Router 不再穿透呼叫 _repository
C3: CD Step 1b sed 替換 IMAGE_TAG_PLACEHOLDER，消除失敗中斷風險
M3: repair-bot 110/188 regex 統一 [a-z0-9][a-z0-9-]{0,30}，禁止底線
m1: defaultMode 0400 加八進位說明注釋
m2: _ssh_execute 用 deadline 計算剩餘 timeout

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

apps/api/src/services/playbook_service.py

@@ -411,6 +411,11 @@ class PlaybookService:
 
     # === CRUD Proxies ===
 
+    # 2026-04-05 Claude Code: C2 修正 — 提供 create() proxy，Router 不再直接呼叫 _repository
+    async def create(self, playbook: Playbook) -> Playbook:
+        """直接建立 Playbook（管理/seed 用途）"""
+        return await self._repository.create(playbook)
+
     async def get_by_id(self, playbook_id: str) -> Playbook | None:
         """取得 Playbook"""
         return await self._repository.get_by_id(playbook_id)