Add runtime filter, kid-friendly toggle, surprise me, and re-roll

- Runtime quick-select buttons (Any/90m/2h/2.5h) filter movies by length
- Kid-friendly toggle forces PG-13 max and boosts Family/Animation genres
- Surprise Me picks a random mood prompt from 20 curated options
- Show Me More re-rolls same mood excluding already-shown movies
- Re-roll appends new results to the existing search history entry

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

app/static/styles.css

@@ -31,3 +31,22 @@
     border-color: #374151;
     color: #6b7280;
 }
+
+.runtime-btn {
+    cursor: pointer;
+}
+.runtime-btn.active {
+    background: rgba(99, 102, 241, 0.3);
+    border-color: #6366f1;
+    color: #c7d2fe;
+}
+.runtime-btn:not(.active):hover {
+    border-color: #4b5563;
+    color: #9ca3af;
+}
+
+#kid-friendly-btn.active {
+    background: rgba(34, 197, 94, 0.2);
+    border-color: #22c55e;
+    color: #86efac;
+}