feat(api): 統一使用台北時區 UTC+8 (禁止 UTC)

- 新增 src/utils/timezone.py 時區工具函式
- 修改 11 個後端檔案，全部改用 now_taipei()
- 更新 HARD_RULES.md 加入時區鐵律章節
- 更新 Skills 02/04 加入時區禁令

🔴 HARD RULE: 禁止 datetime.utcnow() / datetime.now(UTC)
✅ 正確做法: from src.utils.timezone import now_taipei

Memory: feedback_timezone_taipei.md

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

apps/api/src/plugins/finops/cost_analyzer.py

@@ -14,7 +14,9 @@ Phase 3.3: 商業變現能力 - Day-1 ROI
 
 import logging
 from dataclasses import dataclass, field
-from datetime import datetime, timedelta
+from datetime import timedelta
+
+from src.utils.timezone import now_taipei
 from enum import Enum
 from typing import Literal
 
@@ -232,7 +234,7 @@ class IdleResourceScanner:
             CostReport 包含所有浪費資源與建議動作
         """
         self._scan_counter += 1
-        scan_id = f"scan-{self._scan_counter:04d}-{datetime.utcnow().strftime('%Y%m%d%H%M%S')}"
+        scan_id = f"scan-{self._scan_counter:04d}-{now_taipei().strftime('%Y%m%d%H%M%S')}"
 
         logger.info(f"[FinOps] Starting full scan: {scan_id}")
 
@@ -254,7 +256,7 @@ class IdleResourceScanner:
 
         report = CostReport(
             scan_id=scan_id,
-            scanned_at=datetime.utcnow(),
+            scanned_at=now_taipei(),
             cluster_name=cluster_name,
             total_wasted_usd=total_wasted,
             total_resources_scanned=self._get_mock_total_resources(),
@@ -288,23 +290,23 @@ class IdleResourceScanner:
                 "namespace": "database",
                 "size_gb": 500,
                 "storage_class": "gp3",
-                "created": datetime.utcnow() - timedelta(days=90),
-                "last_used": datetime.utcnow() - timedelta(days=60),
+                "created": now_taipei() - timedelta(days=90),
+                "last_used": now_taipei() - timedelta(days=60),
             },
             {
                 "name": "logs-elasticsearch-2023",
                 "namespace": "logging",
                 "size_gb": 200,
                 "storage_class": "gp2",
-                "created": datetime.utcnow() - timedelta(days=180),
-                "last_used": datetime.utcnow() - timedelta(days=120),
+                "created": now_taipei() - timedelta(days=180),
+                "last_used": now_taipei() - timedelta(days=120),
             },
             {
                 "name": "cache-redis-temp",
                 "namespace": "default",
                 "size_gb": 50,
                 "storage_class": "gp3",
-                "created": datetime.utcnow() - timedelta(days=30),
+                "created": now_taipei() - timedelta(days=30),
                 "last_used": None,
             },
         ]
@@ -348,8 +350,8 @@ class IdleResourceScanner:
                 "cpu_request": 2.0,  # vCPU
                 "mem_request_gb": 4.0,
                 "avg_cpu_percent": 0.3,
-                "created": datetime.utcnow() - timedelta(days=120),
-                "last_active": datetime.utcnow() - timedelta(days=45),
+                "created": now_taipei() - timedelta(days=120),
+                "last_active": now_taipei() - timedelta(days=45),
             },
             {
                 "name": "test-worker-batch-xyz99",
@@ -357,8 +359,8 @@ class IdleResourceScanner:
                 "cpu_request": 1.0,
                 "mem_request_gb": 2.0,
                 "avg_cpu_percent": 0.1,
-                "created": datetime.utcnow() - timedelta(days=60),
-                "last_active": datetime.utcnow() - timedelta(days=30),
+                "created": now_taipei() - timedelta(days=60),
+                "last_active": now_taipei() - timedelta(days=30),
             },
             {
                 "name": "debug-shell-admin",
@@ -366,8 +368,8 @@ class IdleResourceScanner:
                 "cpu_request": 0.5,
                 "mem_request_gb": 1.0,
                 "avg_cpu_percent": 0.0,
-                "created": datetime.utcnow() - timedelta(days=14),
-                "last_active": datetime.utcnow() - timedelta(days=10),
+                "created": now_taipei() - timedelta(days=14),
+                "last_active": now_taipei() - timedelta(days=10),
             },
         ]
 
@@ -420,7 +422,7 @@ class IdleResourceScanner:
                 "requested_mem_gb": 48.0,
                 "actual_cpu": 2.0,
                 "actual_mem_gb": 8.0,
-                "created": datetime.utcnow() - timedelta(days=200),
+                "created": now_taipei() - timedelta(days=200),
             },
             {
                 "name": "worker-gpu-unused",
@@ -431,7 +433,7 @@ class IdleResourceScanner:
                 "requested_mem_gb": 16.0,
                 "actual_cpu": 0.5,
                 "actual_mem_gb": 2.0,
-                "created": datetime.utcnow() - timedelta(days=90),
+                "created": now_taipei() - timedelta(days=90),
             },
         ]
 
@@ -468,7 +470,7 @@ class IdleResourceScanner:
                 ),
                 monthly_cost_usd=monthly_cost,
                 created_at=node["created"],
-                last_used_at=datetime.utcnow(),
+                last_used_at=now_taipei(),
                 spec={
                     "totalCpu": node["total_cpu"],
                     "totalMemoryGb": node["total_mem_gb"],