Configurable legend caption for normalized heatmap boards

app.py

@@ -807,9 +807,12 @@ def render_board_html(board: dict, lic: str = "all", fname: str = "board") -> st
                   f"<span class='legend-bar'></span><span class='legend-end'>{html.escape(ends[1])}</span>"
                   + (f"<span>{html.escape(cap)}</span>" if cap else "") + "</div>")
     elif hm:
+        # normalized boards default to explaining the per-column scaling; a
+        # board-supplied "legend" caption overrides it
+        cap = (hm.get("legend") or "scaled per column").strip()
         legend = ("<div class='legend'><span class='legend-end'>worst</span>"
                   "<span class='legend-bar'></span><span class='legend-end'>best</span>"
-                  "<span>scaled per column</span></div>")
+                  f"<span>{html.escape(cap)}</span></div>")
     else:
         legend = ("<div class='legend'><span class='legend-end'>1</span>"
                   "<span class='legend-bar'></span><span class='legend-end'>5</span>"