fix: migrate to Gradio 6.0 launch() API for css and title

In Gradio 6.0, css, title, and theme parameters moved from gr.Blocks()
constructor to the .launch() method. Updated app.py accordingly.

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

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

src/ui/app.py

@@ -30,13 +30,9 @@ def get_gpu_status() -> str:
 
 def create_app() -> gr.Blocks:
     """Create and return the main Gradio application."""
-    css = get_css()
-
     # Gradio 6.0+ compatible Blocks initialization
-    with gr.Blocks(
-        css=css,
-        title="Real-ESRGAN Upscaler",
-    ) as app:
+    # Note: css and title moved to launch() per Gradio 6.0 API
+    with gr.Blocks() as app:
         # Header
         gr.HTML(
             """
@@ -91,6 +87,9 @@ def launch_app():
     logger.info("Starting Real-ESRGAN Web UI...")
     logger.info(get_gpu_status())
 
+    # Get CSS for launch
+    css = get_css()
+
     # Create and launch app
     app = create_app()
 
@@ -100,10 +99,12 @@ def launch_app():
         max_size=config.max_queue_size,
     )
 
-    # Launch server
+    # Launch server (Gradio 6.0: css and title go here)
     app.launch(
         server_name=config.server_name,
         server_port=config.server_port,
         share=config.share,
         show_error=True,
+        css=css,
+        app_kwargs={"title": "Real-ESRGAN Upscaler"},
     )