refactor: remove mock trading functionality from backend and frontend

Removes all mock price simulation features:
- Delete MockPriceManager from backend/data/
- Remove mock_mode, enable_mock, is_mock_mode flags from services
- Remove mock CLI options and config
- Remove mock mode UI components and state from frontend
- Update tests to remove mock references

Now system supports only live and backtest modes.

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

backend/main.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 """
 Main Entry Point
-Supports: backtest, live, mock modes
+Supports: backtest, live modes
 """
 import argparse
 import asyncio
@@ -231,11 +231,8 @@ async def run_with_gateway(args):
     market_service = MarketService(
         tickers=tickers,
         poll_interval=args.poll_interval,
-        mock_mode=args.mock and not is_backtest,
         backtest_mode=is_backtest,
-        api_key=os.getenv("FINNHUB_API_KEY")
-        if not args.mock and not is_backtest
-        else None,
+        api_key=os.getenv("FINNHUB_API_KEY") if not is_backtest else None,
         backtest_start_date=args.start_date if is_backtest else None,
         backtest_end_date=args.end_date if is_backtest else None,
     )
@@ -320,7 +317,6 @@ async def run_with_gateway(args):
         scheduler_callback=scheduler_callback,
         config={
             "mode": args.mode,
-            "mock_mode": args.mock,
             "backtest_mode": is_backtest,
             "tickers": tickers,
             "config_name": config_name,
@@ -353,8 +349,7 @@ def main():
     """Main entry point"""
     parser = argparse.ArgumentParser(description="Trading System")
     parser.add_argument("--mode", choices=["live", "backtest"], default="live")
-    parser.add_argument("--mock", action="store_true")
-    parser.add_argument("--config-name", default="mock")
+    parser.add_argument("--config-name", default="live")
     parser.add_argument("--host", default="0.0.0.0")
     parser.add_argument("--port", type=int, default=8765)
     parser.add_argument(