Add repo names to heatmap tooltip

Extends the JSON response to include per-day repo names via
array_agg on action.repo_name, and surfaces them in the hover
tooltip below the contribution count.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/profile-snippet.tmpl

@@ -56,7 +56,7 @@
     return;
   }
 
-  const byDate = Object.fromEntries(data.map(d => [d.date, d.count]));
+  const byDate = Object.fromEntries(data.map(d => [d.date, d]));
   const bucket = c =>
     c === 0 ? 0 : c < 3 ? 1 : c < 6 ? 2 : c < 10 ? 3 : 4;
 
@@ -85,10 +85,13 @@
     if (d > today) {
       cell.classList.add('future');
     } else {
-      const c = byDate[fmt(d)] || 0;
+      const entry = byDate[fmt(d)];
+      const c = entry ? entry.count : 0;
+      const repos = entry && entry.repos && entry.repos.length ? entry.repos : [];
       cell.dataset.level = String(bucket(c));
       // Native browser tooltip. For richer ones, swap in Tippy.js etc.
-      cell.title = `${fmt(d)}: ${c} contribution${c === 1 ? '' : 's'}`;
+      const repoLine = repos.length ? '\n' + repos.join('\n') : '';
+      cell.title = `${fmt(d)}: ${c} contribution${c === 1 ? '' : 's'}${repoLine}`;
     }
     frag.appendChild(cell);
   }