Refactor figures_to_html to use PlotlyJS embedding for rendering figures, improving display and reducing SVG usage.

app.py

@@ -549,22 +549,18 @@ def make_trend_figs_by_tag(
     return out
 
 def figures_to_html(figs_by_tag: Dict[str, go.Figure]) -> str:
-    """
-    各 Figure を SVG に変換してインラインで並べる（<script>不要で確実に表示）。
-    """
-    if not figs_by_tag:
-        return "<p>図がありません。</p>"
+    """PlotlyJS埋め込み方式（ブラウザ側で描画）"""
     parts = []
+    first = True
     for tag, fig in figs_by_tag.items():
-        # 必要なら width/height/scale を調整可
-        svg_bytes = pio.to_image(fig, format="svg", engine="kaleido")
-        svg = svg_bytes.decode("utf-8")
+        html = pio.to_html(fig, include_plotlyjs='cdn' if first else False, full_html=False)
         parts.append(
             f'<div style="margin:16px 0;border:1px solid #e5e7eb;border-radius:8px;padding:8px">'
             f'<div style="font-weight:600;margin:4px 0 8px 0;">{tag}</div>'
-            f'{svg}'
+            f'{html}'
             f'</div>'
         )
+        first = False
     return "\n".join(parts)
 
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