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/news_fetcher/main.py

@@ -7,6 +7,7 @@ to the ``news:raw`` Redis Stream.
 
 import asyncio
 import logging
+import signal
 
 from redis.asyncio import Redis
 
@@ -53,9 +54,10 @@ async def _poll_rss(
     publisher: StreamPublisher,
     articles_fetched_counter,
     fetch_errors_counter,
+    shutdown_event: asyncio.Event,
 ) -> None:
     """Continuously poll RSS feeds at *interval* seconds."""
-    while True:
+    while not shutdown_event.is_set():
         try:
             logger.info("Polling RSS feeds …")
             articles = await source.fetch()
@@ -66,7 +68,11 @@ async def _poll_rss(
         except Exception:
             logger.exception("RSS poll cycle failed")
             fetch_errors_counter.add(1)
-        await asyncio.sleep(interval)
+        try:
+            await asyncio.wait_for(shutdown_event.wait(), timeout=interval)
+            return  # Shutdown signaled
+        except asyncio.TimeoutError:
+            pass  # Normal timeout — continue polling
 
 
 async def _poll_reddit(
@@ -76,9 +82,10 @@ async def _poll_reddit(
     publisher: StreamPublisher,
     articles_fetched_counter,
     fetch_errors_counter,
+    shutdown_event: asyncio.Event,
 ) -> None:
     """Continuously poll Reddit at *interval* seconds."""
-    while True:
+    while not shutdown_event.is_set():
         try:
             logger.info("Polling Reddit …")
             articles = await source.fetch()
@@ -89,7 +96,11 @@ async def _poll_reddit(
         except Exception:
             logger.exception("Reddit poll cycle failed")
             fetch_errors_counter.add(1)
-        await asyncio.sleep(interval)
+        try:
+            await asyncio.wait_for(shutdown_event.wait(), timeout=interval)
+            return  # Shutdown signaled
+        except asyncio.TimeoutError:
+            pass  # Normal timeout — continue polling
 
 
 async def run() -> None:
@@ -124,28 +135,40 @@ async def run() -> None:
         min_score=config.reddit_min_score,
     )
 
+    # 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)
+
     # Run pollers concurrently
-    async with asyncio.TaskGroup() as tg:
-        tg.create_task(
-            _poll_rss(
-                rss_source,
-                config.rss_poll_interval_seconds,
-                redis,
-                publisher,
-                articles_fetched_counter,
-                fetch_errors_counter,
+    try:
+        async with asyncio.TaskGroup() as tg:
+            tg.create_task(
+                _poll_rss(
+                    rss_source,
+                    config.rss_poll_interval_seconds,
+                    redis,
+                    publisher,
+                    articles_fetched_counter,
+                    fetch_errors_counter,
+                    shutdown_event,
+                )
             )
-        )
-        tg.create_task(
-            _poll_reddit(
-                reddit_source,
-                config.reddit_poll_interval_seconds,
-                redis,
-                publisher,
-                articles_fetched_counter,
-                fetch_errors_counter,
+            tg.create_task(
+                _poll_reddit(
+                    reddit_source,
+                    config.reddit_poll_interval_seconds,
+                    redis,
+                    publisher,
+                    articles_fetched_counter,
+                    fetch_errors_counter,
+                    shutdown_event,
+                )
             )
-        )
+    finally:
+        await redis.aclose()
+        logger.info("News fetcher stopped gracefully")
 
 
 if __name__ == "__main__":