Fix async/await issues in MCP server entry point

- Change create_mcp_server() from async to sync function
- Replace httpx.AsyncClient with httpx.Client for OpenAPI spec fetching
- Make main() function synchronous for proper console script entry point
- Remove unsupported capture_keyboard_interrupt parameter from mcp.run()
- Fix "coroutine 'main' was never awaited" RuntimeWarning

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/mcp_mailu/server.py

@@ -689,7 +689,7 @@ def create_mailu_client(base_url: str, api_token: str) -> httpx.AsyncClient:
     )
 
 
-async def create_mcp_server() -> FastMCP:
+def create_mcp_server() -> FastMCP:
     """Create the MCP server with Mailu API integration."""
     
     # Get configuration from environment variables
@@ -707,8 +707,8 @@ async def create_mcp_server() -> FastMCP:
     logger.info(f"Fetching OpenAPI spec from: {spec_url}")
     
     try:
-        async with httpx.AsyncClient() as fetch_client:
-            response = await fetch_client.get(spec_url)
+        with httpx.Client() as fetch_client:
+            response = fetch_client.get(spec_url)
             response.raise_for_status()
             spec = response.json()
             
@@ -789,17 +789,16 @@ async def create_mcp_server() -> FastMCP:
         return mcp
 
 
-async def main():
+def main():
     """Main entry point for the MCP server."""
     logger.info("Starting Mailu MCP Server")
     
     try:
         # Create and run the MCP server
-        mcp = await create_mcp_server()
+        mcp = create_mcp_server()
         
-        await mcp.run(
-            transport="stdio",
-            capture_keyboard_interrupt=True
+        mcp.run(
+            transport="stdio"
         )
         
     except Exception as e:
@@ -808,4 +807,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    main()