feat(api): Phase 16 R3.1-R3.2 Repository 介面定義

新增:
- IApprovalRepository Protocol
- IIncidentRepository Protocol
- ITimelineRepository Protocol

設計: DI 友好的 Protocol 介面，Service 層只依賴抽象

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/repositories/__init__.py

@@ -0,0 +1,26 @@
+"""
+Repository Layer - 資料存取抽象層
+==================================
+Phase 16 R3: 抽取 Repository 層
+
+設計原則:
+- Protocol 介面定義 (DI 用)
+- CRUD 操作封裝
+- Service 層不直接碰 DB/Redis
+
+版本: v1.0
+建立: 2026-03-26 (台北時區)
+建立者: Claude Code (Phase 16 架構重構)
+"""
+
+from src.repositories.interfaces import (
+    IApprovalRepository,
+    IIncidentRepository,
+    ITimelineRepository,
+)
+
+__all__ = [
+    "IApprovalRepository",
+    "IIncidentRepository",
+    "ITimelineRepository",
+]

apps/api/src/repositories/interfaces.py

@@ -0,0 +1,128 @@
+"""
+Repository Interfaces - Protocol 定義
+======================================
+Phase 16 R3: Repository 層 Protocol 介面
+
+設計原則:
+- 使用 Python Protocol 實現 DI
+- Service 層只依賴 Protocol，不依賴具體實作
+- 便於測試 (可注入 Mock Repository)
+
+版本: v1.0
+建立: 2026-03-26 (台北時區)
+建立者: Claude Code (Phase 16 架構重構)
+"""
+
+from datetime import datetime
+from typing import Protocol, runtime_checkable
+from uuid import UUID
+
+from src.models.approval import ApprovalRequest, ApprovalRequestCreate, ApprovalStatus
+from src.models.incident import Incident
+
+
+@runtime_checkable
+class IApprovalRepository(Protocol):
+    """
+    Approval Repository Protocol
+
+    職責: ApprovalRecord CRUD 操作
+    實作: ApprovalDBRepository (PostgreSQL)
+    """
+
+    async def create(self, request: ApprovalRequestCreate) -> ApprovalRequest:
+        """建立新的 Approval"""
+        ...
+
+    async def get_by_id(self, approval_id: UUID) -> ApprovalRequest | None:
+        """根據 ID 取得 Approval"""
+        ...
+
+    async def get_pending(self) -> list[ApprovalRequest]:
+        """取得所有待審核的 Approval"""
+        ...
+
+    async def update_status(
+        self,
+        approval_id: UUID,
+        status: ApprovalStatus,
+        actor: str | None = None,
+    ) -> ApprovalRequest | None:
+        """更新 Approval 狀態"""
+        ...
+
+    async def add_signature(
+        self,
+        approval_id: UUID,
+        signer: str,
+        decision: str,
+        comment: str | None = None,
+    ) -> ApprovalRequest | None:
+        """新增簽核"""
+        ...
+
+
+@runtime_checkable
+class IIncidentRepository(Protocol):
+    """
+    Incident Repository Protocol
+
+    職責: IncidentRecord CRUD 操作
+    實作: IncidentDBRepository (PostgreSQL)
+    """
+
+    async def create(self, incident: Incident) -> Incident:
+        """建立新的 Incident"""
+        ...
+
+    async def get_by_id(self, incident_id: str) -> Incident | None:
+        """根據 ID 取得 Incident"""
+        ...
+
+    async def get_active(self) -> list[Incident]:
+        """取得所有活躍的 Incident"""
+        ...
+
+    async def update(self, incident: Incident) -> Incident | None:
+        """更新 Incident"""
+        ...
+
+    async def upsert(self, incident: Incident) -> bool:
+        """Upsert Incident (存在則更新，不存在則建立)"""
+        ...
+
+
+@runtime_checkable
+class ITimelineRepository(Protocol):
+    """
+    Timeline Repository Protocol
+
+    職責: TimelineEvent CRUD 操作
+    實作: TimelineDBRepository (PostgreSQL)
+    """
+
+    async def add_event(
+        self,
+        approval_id: UUID,
+        event_type: str,
+        actor: str,
+        details: dict | None = None,
+    ) -> bool:
+        """新增 Timeline 事件"""
+        ...
+
+    async def get_events(
+        self,
+        approval_id: UUID,
+        limit: int = 100,
+    ) -> list[dict]:
+        """取得 Approval 的 Timeline 事件"""
+        ...
+
+    async def get_recent_events(
+        self,
+        limit: int = 50,
+        hours: int = 24,
+    ) -> list[dict]:
+        """取得最近的 Timeline 事件"""
+        ...