Add card color system with wrapCard helper and reset support

Introduce localStorage-backed card color assignment for all card types
with a reusable wrapCard() helper that provides consistent card shell
structure (top actions, bottom actions with color picker). Move color
picker from top-right to bottom-right action bar. Add color reset
button to clear card color back to default.

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

server/src/wled_controller/static/css/layout.css

@@ -315,6 +315,20 @@ h2 {
     color: var(--text-secondary);
     cursor: pointer;
 }
+.color-picker-reset {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    margin-top: 6px;
+    padding-top: 6px;
+    border-top: 1px solid var(--border-color);
+    font-size: 0.78rem;
+    color: var(--text-secondary);
+    cursor: pointer;
+}
+.color-picker-reset:hover {
+    color: var(--danger-color);
+}
 .color-picker-custom input[type="color"] {
     width: 28px;
     height: 28px;