refactor(telegram): migrate edm_notifier text path to EventRouter (ADR-019 Phase 5)

services/edm_notifier.py 的 _send_telegram() 處理 EDM 媒體告警，原本 if/else
分流 sendPhoto / sendMessage。

行為變化：
- 純文字分支（無 image_path）：改走 services.event_router.dispatch_sync()
  event_type=edm_media_alert, severity=warning
- 含圖片分支（sendPhoto with multipart file upload）：依 ADR-019 任務指示
  保留直連 Telegram API（EventRouter 不支援 file upload，列為 known skip）
- caller 行為不變，失敗仍 logger.error 不阻斷主線

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/edm_notifier.py

@@ -94,20 +94,41 @@ class EdmNotifier:
             self.logger.error(f"Line 發送失敗: {e}")
 
     def _send_telegram(self, text, image_path):
+        """
+        EDM / 媒體告警 Telegram 出口
+
+        ADR-019 Phase 5：
+        - 純文字（無 image_path）：走 EventRouter dispatch_sync 統一入口
+        - 含圖片（sendPhoto with file upload）：EventRouter 不支援 multipart
+          file upload，保留直連 Telegram API（ADR-019 任務指示中明列為 skip 類別）
+        """
         bot_token = config.TELEGRAM_BOT_TOKEN
         chat_ids = config.TELEGRAM_CHAT_IDS
-        
+
+        # 純文字分支：走 EventRouter
+        if not (image_path and os.path.exists(image_path)):
+            try:
+                from services.event_router import dispatch_sync
+                dispatch_sync(event={
+                    "event_type": "edm_media_alert",
+                    "severity":   "warning",
+                    "source":     "EDMNotifier",
+                    "title":      "EDM 媒體告警",
+                    "summary":    text[:400],
+                    "status":     "media_alert",
+                    "payload":    {"raw_message": text},
+                }, admin_chat_ids=list(chat_ids) if chat_ids else None)
+            except Exception as e:
+                self.logger.error(f"Telegram 發送失敗 (EventRouter): {e}")
+            return
+
+        # 含圖片分支：保留 sendPhoto multipart upload（EventRouter 不支援檔案）
         for chat_id in chat_ids:
             try:
-                if image_path and os.path.exists(image_path):
-                    url = f"https://api.telegram.org/bot{bot_token}/sendPhoto"
-                    with open(image_path, 'rb') as f:
-                        data = {'chat_id': chat_id, 'caption': text}
-                        files = {'photo': f}
-                        requests.post(url, data=data, files=files, timeout=20)
-                else:
-                    url = f"https://api.telegram.org/bot{bot_token}/sendMessage"
-                    data = {'chat_id': chat_id, 'text': text}
-                    requests.post(url, data=data, timeout=10)
+                url = f"https://api.telegram.org/bot{bot_token}/sendPhoto"
+                with open(image_path, 'rb') as f:
+                    data = {'chat_id': chat_id, 'caption': text}
+                    files = {'photo': f}
+                    requests.post(url, data=data, files=files, timeout=20)
             except Exception as e:
                 self.logger.error(f"Telegram 發送失敗 (ChatID: {chat_id}): {e}")