v2.0.14 — ghost + spinner on card move

Moving a card to another bucket took a visible round-trip (PATCH +
reloadAll) during which the card sat unchanged in the source bucket,
leaving the user wondering if the drop registered. Now every
bucket-move path marks the affected cards `.card-moving` as soon as
the action fires: 50% opacity, dark scrim and a centred accent-ring
spinner. The next renderBoard() rebuilds the DOM so the class comes
off automatically — no explicit cleanup needed.

Call sites:
- drag-drop onto a bucket tile (single + multi-select)
- drag onto an existing bucket to nest it (auto-super-bucket create)
- context-menu → Bucket → <target>

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

public/css/style.css

@@ -524,6 +524,36 @@ body.rounded-cards .card-done-badge i { position: static; bottom: auto; right: a
     animation: card-remove 0.25s ease-in forwards;
     pointer-events: none;
 }
+/* Move-in-flight: card ghosted with a spinner overlay while the
+ * PATCH + reloadAll round-trip completes. The pseudo-elements paint
+ * a dim scrim and a centred spinning ring so the origin bucket
+ * clearly shows the card is "leaving". Removed by the next
+ * renderBoard() since the DOM is rebuilt from scratch. */
+.board-card.card-moving {
+    opacity: 0.5;
+    pointer-events: none;
+    position: relative;
+}
+.board-card.card-moving::before {
+    content: "";
+    position: absolute; inset: 0;
+    background: rgba(0, 0, 0, 0.25);
+    z-index: 3;
+    pointer-events: none;
+}
+.board-card.card-moving::after {
+    content: "";
+    position: absolute;
+    top: 50%; left: 50%;
+    width: 22px; height: 22px;
+    margin: -11px 0 0 -11px;
+    border: 2px solid rgba(255, 255, 255, 0.2);
+    border-top-color: var(--t-accent);
+    border-radius: 50%;
+    animation: spin 0.8s linear infinite;
+    z-index: 4;
+    pointer-events: none;
+}
 .box-select {
     position: absolute; border: 1px solid var(--t-accent); background: rgba(56, 189, 248, 0.08);
     pointer-events: none; z-index: 10;