Disable SSR to fix blank page on Spaces; move theme/css to launch()

gradio 6's server-side rendering fails inside the Hugging Face Space
iframe, leaving a blank white page with "Could not resolve app config".
Serve the classic client-rendered frontend via ssr_mode=False instead.
theme/css move from the Blocks constructor to launch(), where gradio 6
expects them (removes the deprecation warning).

app.py

@@ -299,7 +299,7 @@ theme = gr.themes.Soft(
     font=[gr.themes.GoogleFont("Inter"), "ui-sans-serif", "system-ui", "sans-serif"],
 )
 
-with gr.Blocks(title="Document Intelligence — OCR & Structured Data Extraction", theme=theme, css=CUSTOM_CSS) as demo:
+with gr.Blocks(title="Document Intelligence — OCR & Structured Data Extraction") as demo:
     gr.Markdown(
         "# Turn Documents Into Structured Business Data\n"
         "AI-assisted OCR built for construction, compliance, and finance "
@@ -425,4 +425,12 @@ with gr.Blocks(title="Document Intelligence — OCR & Structured Data Extraction
     )
 
 if __name__ == "__main__":
-    demo.launch(allowed_paths=[SAMPLE_DIR])
+    # ssr_mode=False: gradio 6's server-side rendering fails inside the
+    # Hugging Face Space iframe ("Could not resolve app config" on a blank
+    # page), so serve the classic client-rendered frontend instead.
+    demo.launch(
+        theme=theme,
+        css=CUSTOM_CSS,
+        allowed_paths=[SAMPLE_DIR],
+        ssr_mode=False,
+    )