Implement rotated numeric label generation for the arc scale

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/app.py

@@ -491,6 +491,20 @@ def generate_svg(unit, min_val, max_val, left_label, right_label, big_ticks, sma
                 length, width = (MEDIUM_LEN, MEDIUM_W) if j == medium_j else (SMALL_LEN, SMALL_W)
                 parts.append(_tick_line(angle, length, width))
 
+    lx, ly = PIVOT_X, PIVOT_Y - LABEL_RADIUS
+    for k, idx in enumerate(label_indices):
+        angle = big_angles[idx]
+        label = custom_labels[k] if custom_labels else _fmt(big_vals[idx])
+        wrap = f'rotate({angle:.5f},{PIVOT_X:.5f},{PIVOT_Y:.5f})'
+        if use_paths:
+            parts.append('    ' + _text_to_paths(label, lx, ly, label_size, fd,
+                                                  anchor='middle', wrap_transform=wrap))
+        else:
+            parts.append(
+                f'    <text style="font-size:{label_size:.5f}px;font-family:\'{fd.label}\',monospace;fill:#1a1a1a"'
+                f' text-anchor="middle" x="{lx:.5f}" y="{ly:.5f}" transform="{wrap}">{escape(label)}</text>'
+            )
+
     parts += ['  </g>', '</svg>']
     return '\n'.join(parts)