Replace emoji-as-icons in editor chrome with Font Awesome

Unicode emoji/glyphs (Sitesmith's sparkle, lock, close X) render as
tofu on systems without an emoji font. Swap for the FA4 glyphs the
rest of the chrome already uses:
- SitesmithButton/SitesmithModal: sparkle -> fa-magic, lock -> fa-lock
- ContextMenu "Ask Sitesmith" entry: sparkle -> fa-magic (via new
  optional MenuItem.icon field)
- TemplateModal/SitesmithModal close buttons, PagesPanel delete,
  AssetsPanel delete/cancel: ✕ -> fa-times / fa-trash

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/panels/context-menu/ContextMenu.tsx

@@ -16,6 +16,8 @@ interface ContextMenuProps {
 
 interface MenuItem {
   label: string;
+  /** Font Awesome icon suffix (e.g. 'magic' for fa-magic), rendered before the label. */
+  icon?: string;
   shortcut?: string;
   action: () => void;
   danger?: boolean;
@@ -189,7 +191,8 @@ export const ContextMenu: React.FC<ContextMenuProps> = ({
 
   const items: MenuItem[] = [
     {
-      label: '✨ Ask Sitesmith',
+      label: 'Ask Sitesmith',
+      icon: 'magic',
       action: askSitesmith,
       disabled: isRoot,
       dividerAfter: true,
@@ -291,7 +294,10 @@ export const ContextMenu: React.FC<ContextMenuProps> = ({
               (e.target as HTMLElement).style.background = 'transparent';
             }}
           >
-            <span>{item.label}</span>
+            <span>
+              {item.icon && <i className={`fa fa-${item.icon}`} style={{ marginRight: 6, width: 12 }} />}
+              {item.label}
+            </span>
             {item.shortcut && (
               <span
                 style={{