Fix weekend filter: use precise forex market hours (Fri 22:00–Sun 22:00 UTC)

The old `weekday() >= 5` check blocked all of Sunday, but the forex
market reopens Sunday 22:00 UTC (Sydney open). Now uses proper time-based
check so the bot fetches data and generates signals on Sunday evening.

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

data_provider.py

@@ -18,6 +18,21 @@ from config import PlatformConfig, Timeframe, XAUUSD, PAIR_INFO
 logger = logging.getLogger(__name__)
 
 
+def _is_forex_weekend(now=None) -> bool:
+    """Forex market closed: Friday 22:00 UTC → Sunday 22:00 UTC."""
+    if now is None:
+        now = pd.Timestamp.now(tz="UTC")
+    wd = now.weekday()
+    hour = now.hour
+    if wd == 4 and hour >= 22:
+        return True
+    if wd == 5:
+        return True
+    if wd == 6 and hour < 22:
+        return True
+    return False
+
+
 class DataIntegrityError(Exception):
     """Raised when data fails validation checks."""
     pass
@@ -125,7 +140,7 @@ class ForexDataProvider:
 
         now = pd.Timestamp.now(tz="UTC")
 
-        if now.weekday() >= 5:
+        if _is_forex_weekend(now):
             return True
 
         last_bar = df.index[-1]