Fix stdio startup for Claude Desktop compatibility

- Replace asyncio.run() with anyio.run() in serve command: FastMCP uses
  anyio.create_task_group() internally, and anyio.run() ensures the correct
  backend context. asyncio.run() can misbehave on Windows (ProactorEventLoop).
- Add SERVER STARTING / MCP server ready messages to stderr for diagnostics.
- Replace sys.exit(1) with early return + stderr write inside anyio context;
  sys.exit inside anyio.run() is less predictable than a clean return.
- Eagerly import all modules at serve startup so ImportErrors surface on
  stderr immediately instead of silently killing the process.
- Add __main__.py to allow python -m mcp_synology_container invocation.

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

src/mcp_synology_container/cli.py

@@ -284,34 +284,56 @@ async def _run_check(config_path: str | None) -> bool:
 @click.option("--config", "-c", "config_path", type=click.Path(), help="Config file path")
 def serve(config_path: str | None) -> None:
     """Start the MCP server in stdio mode."""
+    sys.stderr.write("SERVER STARTING\n")
+    sys.stderr.flush()
     _configure_logging("warning")
-    asyncio.run(_run_serve(config_path))
+    # Use anyio.run() — FastMCP uses anyio internally (anyio.create_task_group),
+    # and anyio.run() ensures the correct backend context is set up.
+    # asyncio.run() can cause issues on Windows (ProactorEventLoop + anyio).
+    import anyio
+    anyio.run(_run_serve, config_path)
 
 
 async def _run_serve(config_path: str | None) -> None:
     """Initialize and run the MCP server."""
+    # Eagerly import all modules so any ImportError surfaces immediately on stderr
+    # instead of silently killing the process.
     from mcp_synology_container.auth import AuthManager
     from mcp_synology_container.config import load_config
-    from mcp_synology_container.dsm_client import DsmClient
+    from mcp_synology_container.dsm_client import DsmClient, SynologyError
     from mcp_synology_container.server import create_server
 
+    logger.debug("Loading config from: %s", config_path or "default path")
     try:
         config = load_config(config_path)
     except (FileNotFoundError, ValueError) as e:
-        click.echo(click.style(f"Config error: {e}", fg="red"), err=True)
-        sys.exit(1)
+        sys.stderr.write(f"Config error: {e}\n")
+        sys.stderr.flush()
+        return
 
-    async with DsmClient(config.base_url, config.connection.verify_ssl) as client:
-        await client.query_api_info()
-        auth = AuthManager(config)
-        client.set_auth_manager(auth)
-        # Login on startup
-        try:
-            client.sid = await auth.login(client)
-        except Exception as e:
-            logger.error("Initial login failed: %s", e)
-            sys.exit(1)
+    logger.debug("Connecting to %s", config.base_url)
+    try:
+        async with DsmClient(config.base_url, config.connection.verify_ssl) as client:
+            await client.query_api_info()
+            auth = AuthManager(config)
+            client.set_auth_manager(auth)
 
-        mcp_server = create_server(config, client)
-        logger.info("MCP server starting (stdio mode)")
-        await mcp_server.run_stdio_async()
+            try:
+                client.sid = await auth.login(client)
+            except Exception as e:
+                sys.stderr.write(f"Login failed: {e}\n")
+                sys.stderr.flush()
+                return
+
+            logger.debug("Login OK, creating MCP server")
+            mcp_server = create_server(config, client)
+            sys.stderr.write("MCP server ready\n")
+            sys.stderr.flush()
+            await mcp_server.run_stdio_async()
+    except SynologyError as e:
+        sys.stderr.write(f"DSM error during startup: {e}\n")
+        sys.stderr.flush()
+    except Exception as e:
+        sys.stderr.write(f"Fatal error: {e}\n")
+        sys.stderr.flush()
+        raise