Suppress Telegram messages when no actionable signals found

Auto-scan still runs and updates the level cache every cycle,
but only sends to Telegram when quality A+/A/B/C signals exist.

telegram_bot.py

@@ -390,9 +390,14 @@ async def _scan_timeframe(
 
     _update_level_cache(reports)
 
-    summary = _format_scan_summary(reports, tf)
     actionable = [r for r in reports if r.signal_quality in ("A+", "A", "B", "C")]
 
+    if not actionable:
+        logger.info(f"{tf.value} scan: no actionable signals — skipping Telegram message")
+        return
+
+    summary = _format_scan_summary(reports, tf)
+
     for chat_id in list(_autoscan_chats):
         try:
             await bot.send_message(chat_id, summary, parse_mode=ParseMode.MARKDOWN)