fix(ui): resolve Gradio 4 component compatibility and runtime error

app.py

@@ -172,7 +172,7 @@ with gr.Blocks(css=css_content, title="MVM²: Senior UI AI Dashboard") as demo:
         # --- CENTER STAGE: Canvas ---
         with gr.Column(scale=2):
             gr.Markdown("### 🎨 MVM² Verification Canvas")
-            with gr.Box(elem_classes="glass-card"):
+            with gr.Group(elem_classes="glass-card"):
                 canvas_latex = gr.Textbox(label="Canonical LaTeX Transcription", lines=2, interactive=False, elem_classes="monospace")
                 calib_bar_html = gr.HTML()
             
@@ -182,13 +182,13 @@ with gr.Blocks(css=css_content, title="MVM²: Senior UI AI Dashboard") as demo:
         # --- RIGHT PANEL: Signal Intel ---
         with gr.Column(scale=1, variant="panel"):
             gr.Markdown("### ⚡ Signal Intelligence")
-            with gr.Box(elem_classes="glass-card"):
+            with gr.Group(elem_classes="glass-card"):
                 signal_gauges = gr.HTML()
             
             gr.Markdown("### 📄 Educational Assessment")
             download_btn = gr.File(label="Download Diagnostic PDF", elem_classes="download-btn")
             
-            with gr.Box(elem_classes="glass-card", style="margin-top: 20px; border-left: 4px solid #6366f1;"):
+            with gr.Group(elem_classes="glass-card status-box"):
                 gr.Markdown(
                     """
                     **System Status**

theme.css

@@ -113,6 +113,11 @@ h2 { font-weight: 600; color: var(--text-main); }
     filter: drop-shadow(0 4px 6px rgba(0,0,0,0.3));
 }
 
+.status-box {
+    margin-top: 20px !important;
+    border-left: 4px solid var(--primary) !important;
+}
+
 /* Gradio Overrides */
 .stButton button { border-radius: 10px !important; }
 .stMarkdown { color: var(--text-main) !important; }