Tracker: unfold a combatant's stat block inline

- extract the 5e stat-block markup into enemy/_statblock.html.twig
  (sb.block(enemy) macro); the enemy detail page now uses it too
- each tracker combatant gets a "stat block" toggle that expands the
  block in place (Bootstrap collapse), so you don't have to leave the
  encounter to check AC / attacks
- open blocks are remembered in localStorage and re-opened after each
  damage/heal reload, and the caret rotates when expanded

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

assets/styles/app.css

@@ -112,3 +112,15 @@ table.dataTable {
     max-width: 100%;
     height: auto;
 }
+
+/* --- Tracker: unfoldable stat blocks --------------------------------- */
+[data-bs-toggle="collapse"] .sb-caret {
+    display: inline-block;
+    transition: transform 0.15s ease;
+}
+[data-bs-toggle="collapse"][aria-expanded="true"] .sb-caret {
+    transform: rotate(90deg);
+}
+.statblock-collapse h3 {
+    margin-top: 0.75rem;
+}