Fix Claude Desktop loading: lazy NAS connection on first tool call

Previously the server blocked at startup waiting for query_api_info()
and login() before starting the MCP protocol. Claude Desktop has a short
initialization timeout and dropped the server before the handshake started.

Changes:
- DsmClient: add _ensure_initialized() with asyncio.Lock for thread-safe
  lazy init; called automatically at the start of request(), upload_text(),
  and download_text() on the first use.
- cli.py serve: remove upfront query_api_info() and auth.login() calls;
  the server now starts immediately ("MCP server ready" on stderr) and
  connects to the NAS on the first tool invocation.

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

src/mcp_synology_container/cli.py

@@ -300,7 +300,7 @@ async def _run_serve(config_path: str | None) -> None:
     # 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, SynologyError
+    from mcp_synology_container.dsm_client import DsmClient
     from mcp_synology_container.server import create_server
 
     logger.debug("Loading config from: %s", config_path or "default path")
@@ -311,29 +311,19 @@ async def _run_serve(config_path: str | None) -> None:
         sys.stderr.flush()
         return
 
-    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)
+    # Open the HTTP client and register auth — but do NOT connect to the NAS yet.
+    # Lazy init (_ensure_initialized) runs on the first tool call, so Claude Desktop
+    # sees the server as ready immediately without waiting for NAS connectivity.
+    async with DsmClient(config.base_url, config.connection.verify_ssl) as client:
+        auth = AuthManager(config)
+        client.set_auth_manager(auth)
 
-            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()
+        mcp_server = create_server(config, client)
+        sys.stderr.write("MCP server ready\n")
+        sys.stderr.flush()
+        try:
             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
+        except Exception as e:
+            sys.stderr.write(f"MCP server error: {e}\n")
+            sys.stderr.flush()
+            raise