fix(models): 全面替換 datetime.UTC → timezone.utc 相容 Python 3.10

terminal.py, incident.py, utils/timezone.py 同樣問題。
CI runner Python 3.10 無 UTC 常數，導致所有模型靜默 import 失敗。

# 2026-04-06 ogt: 完整修復，不再有漏網之魚

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

apps/api/src/models/incident.py

@@ -20,7 +20,7 @@ C-Suite 戰略會議決議 (2026-03-22):
 - Semantic Memory (Vector DB): 向量化後的知識，供 RAG 檢索
 """
 
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from enum import Enum
 from typing import Literal
 from uuid import UUID, uuid4
@@ -338,7 +338,7 @@ class Incident(BaseModel):
 
     # === 識別 ===
     incident_id: str = Field(
-        default_factory=lambda: f"INC-{datetime.now(UTC).strftime('%Y%m%d')}-{str(uuid4())[:6].upper()}",
+        default_factory=lambda: f"INC-{datetime.now(timezone.utc).strftime('%Y%m%d')}-{str(uuid4())[:6].upper()}",
         description="事件唯一識別碼 (如 INC-20260322-A1B2C3)",
     )
 
@@ -387,11 +387,11 @@ class Incident(BaseModel):
 
     # === 時間軸 ===
     created_at: datetime = Field(
-        default_factory=lambda: datetime.now(UTC),
+        default_factory=lambda: datetime.now(timezone.utc),
         description="事件建立時間",
     )
     updated_at: datetime = Field(
-        default_factory=lambda: datetime.now(UTC),
+        default_factory=lambda: datetime.now(timezone.utc),
         description="最後更新時間",
     )
     resolved_at: datetime | None = Field(

apps/api/src/models/terminal.py

@@ -11,7 +11,7 @@ Pydantic models for Terminal SSE communication.
 @date 2026-03-28 (台北時間)
 """
 
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from enum import Enum
 from typing import Any
 
@@ -110,7 +110,7 @@ class TerminalIntentResponse(BaseModel):
         description="SSE 串流訂閱 URL",
     )
     created_at: datetime = Field(
-        default_factory=lambda: datetime.now(UTC),
+        default_factory=lambda: datetime.now(timezone.utc),
     )
 
 
@@ -248,7 +248,7 @@ class TerminalSession(BaseModel):
     intent: str
     context: SpatialContext
     status: TerminalSessionStatus = TerminalSessionStatus.PENDING
-    created_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
+    created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
     last_event_id: int = 0
     message_count: int = 0
 

apps/api/src/utils/timezone.py

@@ -6,7 +6,7 @@ AWOOOI - 時區工具
 🔴 HARD RULE: 全系統使用台北時區，禁止 UTC
 """
 
-from datetime import UTC, datetime, timedelta, timezone
+from datetime import datetime, timedelta, timezone
 
 # 台北時區 (UTC+8)
 TAIPEI_TZ = timezone(timedelta(hours=8))
@@ -38,7 +38,7 @@ def to_taipei(dt: datetime) -> datetime:
     """
     if dt.tzinfo is None:
         # naive datetime，假設是 UTC
-        dt = dt.replace(tzinfo=UTC)
+        dt = dt.replace(tzinfo=timezone.utc)
     return dt.astimezone(TAIPEI_TZ)