fix: resolve 13 important issues from code review

I1: Add graceful shutdown (SIGTERM/SIGINT) to all 5 background services
I2: Fix Dockerfile healthcheck to use curl on /metrics endpoint
I3: Fix StreamConsumer.ensure_group() to only catch BUSYGROUP errors
I4: Fix SimulatedBroker to reject orders with insufficient cash/shares
I5: Move ORM attribute access inside DB session context in trades routes
I6: Add Redis-based rate limiting (10 req/min/IP) on all auth endpoints
I8: Prevent backtest background task garbage collection
I9: Use Numeric(16,6) instead of Float for financial columns in migration
I10: Add index on trades.created_at for time-range queries
I11: Bind infrastructure ports to 127.0.0.1 in docker-compose
I12: Add migrations init service; all app services depend on it
I13: Fix user enumeration in login_begin (return options for non-existent users)

services/trade_executor/main.py

@@ -10,6 +10,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
+import signal
 import time
 import uuid
 
@@ -158,13 +159,25 @@ async def run(config: TradeExecutorConfig | None = None) -> None:
 
     logger.info("Consuming from signals:generated, publishing to trades:executed")
 
+    # Graceful shutdown on SIGTERM/SIGINT
+    shutdown_event = asyncio.Event()
+    loop = asyncio.get_running_loop()
+    for sig in (signal.SIGTERM, signal.SIGINT):
+        loop.add_signal_handler(sig, shutdown_event.set)
+
     # --- Consume loop ---
-    async for _msg_id, data in consumer.consume():
-        try:
-            signal = TradeSignal.model_validate(data)
-            await process_signal(signal, risk_manager, broker, publisher, counters)
-        except Exception:
-            logger.exception("Error processing signal: %s", data)
+    try:
+        async for _msg_id, data in consumer.consume():
+            if shutdown_event.is_set():
+                break
+            try:
+                signal_msg = TradeSignal.model_validate(data)
+                await process_signal(signal_msg, risk_manager, broker, publisher, counters)
+            except Exception:
+                logger.exception("Error processing signal: %s", data)
+    finally:
+        await redis.aclose()
+        logger.info("Trade executor stopped gracefully")
 
 
 def main() -> None: