fix: graceful SIGTERM shutdown for IRC and Mumble bots

Send IRC QUIT before closing the socket so the server releases the nick
immediately. Wrap readline() in wait_for(timeout=2.0) so the _running
check triggers even when the server is quiet. Explicitly stop pymumble
in the signal handler to accelerate Mumble teardown. Together these
eliminate the 10s podman grace-period SIGKILL.

src/derp/bot.py

@@ -253,7 +253,10 @@ class Bot:
     async def _loop(self) -> None:
         """Read and dispatch messages until disconnect."""
         while self._running:
-            line = await self.conn.readline()
+            try:
+                line = await asyncio.wait_for(self.conn.readline(), timeout=2.0)
+            except asyncio.TimeoutError:
+                continue
             if line is None:
                 log.warning("server closed connection")
                 return

src/derp/cli.py

@@ -10,6 +10,7 @@ import sys
 from derp import __version__
 from derp.bot import Bot
 from derp.config import build_server_configs, resolve_config
+from derp.irc import format_msg
 from derp.log import JsonFormatter
 from derp.plugin import PluginRegistry
 
@@ -72,12 +73,24 @@ def _run(bots: list) -> None:
 
 
 def _shutdown(bots: list) -> None:
-    """Signal handler: stop all bot loops so cProfile can flush."""
+    """Signal handler: stop all bot loops and tear down connections."""
     logging.getLogger("derp").info("SIGTERM received, shutting down")
+    loop = asyncio.get_running_loop()
     for bot in bots:
         bot._running = False
-        if hasattr(bot, "conn"):
-            asyncio.get_running_loop().create_task(bot.conn.close())
+        if hasattr(bot, "conn") and bot.conn.connected:
+            loop.create_task(_quit_and_close(bot))
+        elif hasattr(bot, "_mumble") and bot._mumble:
+            bot._mumble.stop()
+
+
+async def _quit_and_close(bot) -> None:
+    """Send IRC QUIT and close the connection."""
+    try:
+        await bot.conn.send(format_msg("QUIT", "shutting down"))
+    except Exception:
+        pass
+    await bot.conn.close()
 
 
 def _dump_tracemalloc(log: logging.Logger, path: str, limit: int = 25) -> None: