fix: 3 個飛輪沉默未打通節點 — 統帥截圖盤出

統帥截圖證據 (Telegram MEDIUM 告警仍走人工審核):
INC-20260411-A03B2E / A2BB29 顯示「[規則匹配]」+ action=unknown-service

節點 1: AutoApprovePolicy 擋下規則匹配 (飛輪主因)
  - ADR-073 規則匹配 confidence=0.0 (防偽造)
  - AutoApprovePolicy.min_confidence=0.50 → 擋下
  - 結果: MEDIUM 規則匹配永遠人工審核，飛輪不轉
  修復: auto_approve.py 加 _is_rule_based 判斷
        (is_rule_based / source=expert_system / rule_id / matched_rule)
        → bypass min_confidence 檢查
        → 驗證: should_auto_approve=True ✅

節點 2: _is_bad_target 漏 unknown-service magic string
  - _resolve_target_from_k8s fallback 產 unknown-service / unknown-pod
  - GAP-A4 Phase 1/2 只擋 'unknown' 而非前綴
  修復: alert_rule_engine.py 加 unknown-/none-/null-/undefined- 前綴黑名單
        → 驗證: 4 個 magic 全 bad ✅

節點 3: stale_ready_tokens_resend 無時效過濾
  - 截圖是 2026-04-11 (4 天前) 告警
  - 舊 labels 過期，重 process 也產不出新 target
  - 壓爆 Ollama + 污染 Telegram 卡片
  修復: decision_manager.py 跳過 > 3 天的 stale incident
        → skip + log stale_ready_token_skipped_too_old

回歸: 113/113

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

apps/api/src/services/decision_manager.py

@@ -2150,6 +2150,27 @@ class DecisionManager:
                         if str(getattr(incident, "status", "")).lower() in ("resolved", "closed"):
                             continue
 
+                        # 2026-04-15 Claude Sonnet 4.6 (節點 3 修復):
+                        # 跳過 > 3 天的 stale incident — labels 已過時，重 process 無意義
+                        # 只會壓爆 Ollama + 污染 Telegram 卡片（截圖：4/11 的卡片今天還在彈）
+                        _STALE_DAYS = 3
+                        _created_at = getattr(incident, "created_at", None)
+                        if _created_at:
+                            from datetime import datetime as _dt, timedelta as _td, timezone as _tz
+                            _now = _dt.now(_tz.utc)
+                            _cutoff = _now - _td(days=_STALE_DAYS)
+                            # 確保 _created_at 有時區
+                            if _created_at.tzinfo is None:
+                                _created_at = _created_at.replace(tzinfo=_tz.utc)
+                            if _created_at < _cutoff:
+                                logger.debug(
+                                    "stale_ready_token_skipped_too_old",
+                                    incident_id=incident_id,
+                                    age_days=(_now - _created_at).days,
+                                    cutoff_days=_STALE_DAYS,
+                                )
+                                continue
+
                         proposal_data = data.get("proposal_data") or {}
                         if not proposal_data:
                             continue