UX: CSV/SVG download links, schema preview on load, cleaner SVG theme

src/visualization/svg_theme.py

@@ -43,6 +43,7 @@ def apply_theme(svg: str) -> str:
     if not svg or "<svg" not in svg:
         return svg
 
+    svg = _strip_plotly_chrome(svg)
     svg = _ensure_viewbox(svg)
     svg = _ensure_responsive(svg)
     svg = _normalize_fonts(svg)
@@ -51,6 +52,25 @@ def apply_theme(svg: str) -> str:
     return svg
 
 
+def _strip_plotly_chrome(svg: str) -> str:
+    """Remove Plotly's modebar, watermark and toolbar artifacts."""
+    # Plotly draws a modebar group — strip it
+    svg = re.sub(
+        r'<g[^>]*class="[^"]*modebar[^"]*"[^>]*>.*?</g>',
+        "",
+        svg,
+        flags=re.DOTALL,
+    )
+    # Remove explicit white backgrounds that Plotly adds
+    svg = re.sub(
+        r'fill="(?:rgb\(255,\s*255,\s*255\)|#fff(?:fff)?|white)"',
+        'fill="transparent"',
+        svg,
+        flags=re.IGNORECASE,
+    )
+    return svg
+
+
 def _ensure_viewbox(svg: str) -> str:
     """If width/height are present but viewBox is missing, derive it."""
     if re.search(r"viewBox\s*=", svg, re.IGNORECASE):