Add missing Gradio UI components and demo.launch() to complete app initialization

CRITICAL FIX: Resolved "application does not seem to be initialized" runtime error.

Root Cause: After fixing the indentation errors, the app.py file was missing the Gradio UI implementation inside the `with gr.Blocks()` context. The file ended at line 161 with just data variable declarations, but had no UI components or launch statement.

Changes Made:
- Added tabbed interface using gr.Tabs() with 4 tabs:
1. Consent/Event Audit tab
2. Cadence Branching Composer tab
3. Live Diagnostics tab
4. Audit Trail Export tab
- Each tab calls its corresponding panel function with sample data
- Added `if __name__ == "__main__":` block with `demo.launch()` to properly initialize and start the Gradio application

This completes the application structure and should resolve the initialization error.

app.py

@@ -158,4 +158,21 @@ diagnostics_sample = [
         }
     ]
     
-audit_history_sample = consent_events_sample
+audit_history_sample = consent_events_sample
+
+    # Create tabbed interface
+    with gr.Tabs():
+        with gr.Tab("Consent/Event Audit"):
+            consent_audit_panel(consent_events_sample)
+        
+        with gr.Tab("Cadence Branching Composer"):
+            branching_composer(branches_sample)
+        
+        with gr.Tab("Live Diagnostics"):
+            diagnostics_panel(diagnostics_sample)
+        
+        with gr.Tab("Audit Trail Export"):
+            audit_trail_widget(audit_history_sample)
+
+if __name__ == "__main__":
+    demo.launch()