Add Telegram bot and fix excessive API calls

- Add telegram_bot.py: full bot interface with /scan, /signals, /pair,
  /all, /tf, /watch, /unwatch, /status, /help commands; per-chat state;
  background thread pool for analysis; auto message splitting
- Fix data_provider: warn once per symbol with no API data and cache
  synthetic fallback to prevent redundant individual API calls
- Fix signal_aggregator: derive spread estimate from already-fetched
  primary DataFrame instead of making a separate M5 API call per pair
- Add python-telegram-bot[job-queue]>=20.0 to requirements.txt

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

data_provider.py

@@ -73,6 +73,7 @@ class ForexDataProvider:
         self._cache: Dict[str, pd.DataFrame] = {}
         self._cache_timestamps: Dict[str, float] = {}
         self._request_times: deque = deque()  # timestamps of recent API credits used
+        self._no_api_data: set = set()  # td_symbols with no values from API (use synthetic)
         self._session = requests.Session()
         self._session.headers.update({
             "User-Agent": "Mozilla/5.0 (compatible; ForexIntel/1.0)"
@@ -281,7 +282,20 @@ class ForexDataProvider:
 
                 values = sym_data.get("values")
                 if not values:
-                    logger.warning(f"No values in batch response for {td_sym}")
+                    if td_sym not in self._no_api_data:
+                        logger.warning(
+                            f"No API data for {td_sym} — using synthetic data"
+                        )
+                        self._no_api_data.add(td_sym)
+                    # Cache synthetic so fetch_ohlcv won't make a redundant API call
+                    try:
+                        syn = self._generate_synthetic_data(symbol, timeframe, lookback_days)
+                        syn = self._validate_and_clean(syn, symbol, timeframe)
+                        cache_key = f"{symbol}_{timeframe.value}"
+                        self._cache[cache_key] = syn
+                        self._cache_timestamps[cache_key] = now
+                    except Exception:
+                        pass
                     continue
 
                 records = [