fix(telegram): 歷史按鈕改從 AnomalyCounter(Redis) 讀頻率，修復永遠顯示「無頻率統計資料」

根本原因: frequency_stats 從未持久化到 DB，get_by_id() 回傳永遠是 None
修復: 用 AnomalyCounter.derive_key_from_incident() 推導 anomaly_key，
直接從 Redis 查即時頻率與處置分佈統計

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

apps/api/src/services/telegram_gateway.py

@@ -2655,9 +2655,10 @@ class TelegramGateway:
         """
         ADR-050 P2: 傳送事件頻率統計訊息
 
-        2026-04-01 Claude Code (ADR-050 P2): history button handler
+        2026-04-10 ogt: 修復 — frequency_stats 不存 DB，改從 AnomalyCounter (Redis) 即時查詢
         """
         from src.repositories.incident_repository import get_incident_repository
+        from src.services.anomaly_counter import get_anomaly_counter, AnomalyCounter
 
         try:
             repo = get_incident_repository()
@@ -2667,47 +2668,60 @@ class TelegramGateway:
                 await self.send_notification(f"⚠️ 找不到事件 <code>{html.escape(incident_id)}</code>")
                 return
 
-            fs = incident.frequency_stats
-            if not fs:
+            # frequency_stats 不持久化，從 AnomalyCounter (Redis) 即時查詢
+            anomaly_key = AnomalyCounter.derive_key_from_incident(incident)
+            if not anomaly_key:
                 await self.send_notification(
-                    f"📊 <b>事件歷史</b>\n\n🔖 <code>{html.escape(incident.incident_id)}</code>\n\n無頻率統計資料"
+                    f"📊 <b>事件歷史</b>\n\n🔖 <code>{html.escape(incident_id)}</code>\n\n⚠️ 無法推導告警鍵（signals 為空）"
                 )
                 return
 
+            counter = get_anomaly_counter()
+            freq = await counter.record_anomaly({
+                "alert_name": incident.signals[0].alert_name if incident.signals else "",
+                "service": incident.affected_services[0] if incident.affected_services else "",
+                "namespace": (incident.signals[0].labels or {}).get("namespace", "") if incident.signals else "",
+                "error_type": (incident.signals[0].labels or {}).get("reason", (incident.signals[0].labels or {}).get("error_type", "")) if incident.signals else "",
+            })
+            disposition = await counter.get_disposition_stats(anomaly_key)
+
             lines = [
                 f"📊 <b>事件歷史統計</b>",
                 f"",
-                f"🔖 <code>{html.escape(incident.incident_id)}</code>",
-                f"🔑 告警鍵: <code>{html.escape(fs.anomaly_key[:60])}</code>",
+                f"🔖 <code>{html.escape(incident_id)}</code>",
+                f"🔑 告警鍵: <code>{html.escape(anomaly_key)}</code>",
                 f"",
                 f"⏱ <b>發生頻率</b>",
-                f"  1小時: {fs.count_1h} 次",
-                f"  24小時: {fs.count_24h} 次",
-                f"  7天: {fs.count_7d} 次",
-                f"  30天: {fs.count_30d} 次",
+                f"  1小時: {freq.count_1h} 次",
+                f"  24小時: {freq.count_24h} 次",
+                f"  7天: {freq.count_7d} 次",
+                f"  30天: {freq.count_30d} 次",
             ]
 
-            if fs.auto_repair_count > 0:
+            if freq.auto_repair_count > 0:
                 lines += [
                     f"",
                     f"🔧 <b>自動修復</b>",
-                    f"  執行次數: {fs.auto_repair_count}",
+                    f"  執行次數: {freq.auto_repair_count}",
                 ]
-                if fs.last_repair_action:
-                    lines.append(f"  最後動作: {html.escape(fs.last_repair_action[:80])}")
+                if freq.last_repair_action:
+                    lines.append(f"  最後動作: {html.escape(freq.last_repair_action)}")
 
-            # 2026-04-07 Claude Code: Sprint 4 D2 — 處置分佈明細
-            total_res = fs.total_resolution_count
+            # 處置分佈
+            auto_r = disposition.get("auto_repair_count", 0)
+            cold_s = disposition.get("cold_start_trust_count", 0)
+            human_a = disposition.get("human_approved_count", 0)
+            manual_r = disposition.get("manual_resolved_count", 0)
+            total_res = auto_r + cold_s + human_a + manual_r
             if total_res > 0:
-                auto_total = fs.auto_repair_count + fs.cold_start_trust_count
-                auto_rate = int(auto_total / total_res * 100) if total_res > 0 else 0
+                auto_rate = int((auto_r + cold_s) / total_res * 100)
                 lines += [
                     f"",
                     f"📋 <b>處置分佈</b> (共 {total_res} 次)",
-                    f"  🤖 自動修復: {fs.auto_repair_count}",
-                    f"  ❄️ 冷啟動信任: {fs.cold_start_trust_count}",
-                    f"  👤 人工審核: {fs.human_approved_count}",
-                    f"  🔧 手動處理: {fs.manual_resolved_count}",
+                    f"  🤖 自動修復: {auto_r}",
+                    f"  ❄️ 冷啟動信任: {cold_s}",
+                    f"  👤 人工審核: {human_a}",
+                    f"  🔧 手動處理: {manual_r}",
                     f"  📈 自動化率: <b>{auto_rate}%</b>",
                 ]
 
@@ -2715,7 +2729,7 @@ class TelegramGateway:
 
         except Exception as e:
             logger.warning("send_incident_history_failed", incident_id=incident_id, error=str(e))
-            await self.send_notification(f"⚠️ 無法取得歷史統計: {html.escape(str(e)[:100])}")
+            await self.send_notification(f"⚠️ 無法取得歷史統計: {html.escape(str(e))}")
 
     async def _send_reanalyze_result(self, incident_id: str) -> None:
         """