Fix concurrent API credit exhaustion — shared prefetch + dedup warnings

- telegram_bot: one ForexDataProvider shared across all SCAN_TIMEFRAMES;
  combined prefetch of all unique TFs up front so the 4 concurrent scans
  hit the warm cache instead of firing simultaneous API calls
- data_provider: skip prefetch_batch for timeframes already in cache
- data_provider: deduplicate "no data" warning per symbol (fires once, not once per TF)
- data_provider: [live] info log on successful fetch; outlier-removal downgraded to debug

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

data_provider.py

@@ -20,6 +20,7 @@ import requests
 from config import PlatformConfig, Timeframe, SYMBOL_DISPLAY, PIP_VALUES
 
 logger = logging.getLogger(__name__)
+_no_data_warned: set = set()  # suppress duplicate "no data" warnings per symbol
 
 
 class DataIntegrityError(Exception):
@@ -151,7 +152,17 @@ class ForexDataProvider:
         if lookback_days is None:
             lookback_days = self.config.data_lookback_days
 
+        now = time.time()
         for tf in timeframes:
+            cached = all(
+                f"{s}_{tf.value}" in self._cache_timestamps
+                and (now - self._cache_timestamps[f"{s}_{tf.value}"]) < self.config.refresh_interval
+                and not self._cache.get(f"{s}_{tf.value}", pd.DataFrame()).empty
+                for s in symbols
+            )
+            if cached:
+                logger.debug(f"Skipping prefetch for {tf.value} — all {len(symbols)} symbols cached")
+                continue
             try:
                 self._batch_fetch_timeframe(symbols, tf, lookback_days)
                 time.sleep(1.0)  # brief pause between TF requests
@@ -332,10 +343,9 @@ class ForexDataProvider:
 
                 values = sym_data.get("values")
                 if not values:
-                    logger.warning(
-                        f"No data returned by Twelve Data for {td_sym} "
-                        f"— symbol may require a paid plan."
-                    )
+                    if td_sym not in _no_data_warned:
+                        logger.warning(f"No data from Twelve Data for {td_sym} — symbol may require a paid plan.")
+                        _no_data_warned.add(td_sym)
                     continue
 
                 records = [