delete animation, no #inbox tag, preset delete lock on builtins

Card delete animation (public/css/style.css, public/js/modules/board.js):
* @keyframes card-remove: opacity 1→0 + scale(1)→0.85 + translateY(8px),
  250ms ease-in forwards. .card-removing class with pointer-events:none.
* New exported animateCardRemoval(ids) in board.js: adds .card-removing
  to each matching board-card element, resolves after 260ms so the
  caller can await before the API DELETE + _reloadAll.
* Wired into all three delete paths:
  - context-menu.js group delete: animates parent + all children
  - context-menu.js single delete: same path (allCards has one entry)
  - app.js Del/Backspace shortcut: animates all selected cards

Quick capture no #inbox (public/js/app.js):
* Removed the line that auto-injected #inbox into the body of every
  quick-captured card. Cards now land tag-free in the active bucket
  (or unsorted).

Settings: preset delete lock (public/js/modules/theme.js):
* refreshPresetSelect() now disables the delete button (disabled attr
  + opacity 0.35 + cursor not-allowed) when a builtin: preset is
  selected. Re-enabled when a user: preset is selected. The click
  handler already had a startsWith('user:') guard but the button
  wasn't visually locked.

chore: bump version to 0.9.17

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/js/modules/theme.js

@@ -258,6 +258,14 @@ function refreshPresetSelect() {
         sel.appendChild(userGroup);
     }
     if (cur && sel.querySelector(`option[value="${CSS.escape(cur)}"]`)) sel.value = cur;
+    // Disable delete button when a built-in preset is selected
+    const delBtn = $('design-preset-delete');
+    if (delBtn) {
+        const isUser = sel.value?.startsWith('user:');
+        delBtn.disabled = !isUser;
+        delBtn.style.opacity = isUser ? '' : '0.35';
+        delBtn.style.cursor = isUser ? '' : 'not-allowed';
+    }
 }
 
 function getSelectedPreset() {