fix(api): 修復全部 lint 錯誤 (ruff --fix)

- Import sorting (I001)
- Unused imports (F401)
- f-string without placeholders (F541)
- Loop variable unused (B007)
- zip() strict parameter (B905)
- Exception chaining (B904)
- collections.abc imports (UP035)

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

apps/api/src/db/models.py

@@ -278,6 +278,48 @@ class AuditLog(Base):
     )
     dry_run_message: Mapped[str | None] = mapped_column(Text, nullable=True)
 
+    # ==========================================================================
+    # Phase 18: 失敗自動修復閉環欄位 (2026-03-26)
+    # ==========================================================================
+
+    # 授權來源追蹤
+    authorization_channel: Mapped[str | None] = mapped_column(
+        String(20),
+        nullable=True,
+        comment="Authorization source: web, telegram, auto",
+    )
+
+    # 重試與修復追蹤
+    retry_count: Mapped[int] = mapped_column(
+        Integer,
+        default=0,
+        nullable=False,
+        comment="Number of retry attempts",
+    )
+    failure_classification: Mapped[str | None] = mapped_column(
+        String(50),
+        nullable=True,
+        comment="Failure type: TIMEOUT, K8S_ERROR, NETWORK_ERROR, PERMISSION_DENIED",
+    )
+    source_approval_id: Mapped[str | None] = mapped_column(
+        String(36),
+        nullable=True,
+        index=True,
+        comment="Original approval ID if this is a repair attempt",
+    )
+
+    # 自動修復狀態
+    auto_repair_attempted: Mapped[bool] = mapped_column(
+        default=False,
+        nullable=False,
+        comment="Whether auto-repair was attempted",
+    )
+    auto_repair_result: Mapped[str | None] = mapped_column(
+        Text,
+        nullable=True,
+        comment="Auto-repair result: AI analysis and repair outcome",
+    )
+
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),
@@ -290,6 +332,8 @@ class AuditLog(Base):
         Index("ix_audit_operation_type", "operation_type"),
         Index("ix_audit_success", "success"),
         Index("ix_audit_created_at", "created_at"),
+        Index("ix_audit_authorization_channel", "authorization_channel"),  # Phase 18
+        Index("ix_audit_failure_classification", "failure_classification"),  # Phase 18
     )