Improve gitignore rules for data directory to ensure all data files are ignored

.gitignore

@@ -168,12 +168,15 @@ cython_debug/
 # Trading data, logs, and state files
 logs/  # For log files
 data/  # For persistent data like stats, alarms, state
-
-# Specific file ignores (mostly covered by data/ but good to be explicit if needed elsewhere)
-# trading_stats.json # Now covered by data/
-# price_alarms.json # Now covered by data/
-# trading_engine_state.json # Now covered by data/
-demo_stats.json # If this is still used at root, keep it
+data/*  # Explicitly ignore all files in data directory
+data/**/*  # Ignore all subdirectories and files in data
+
+# Specific file ignores (backup in case files exist elsewhere)
+*.sqlite
+*.sqlite3
+price_alarms.json
+trading_stats.sqlite
+trading_engine_state.json
 
 # General log files if not in logs/ directory (already covered by *.log above)
 # *.log