♿️ fix: resolve all svelte-check a11y warnings across web apps

- Fix 121 accessibility warnings across 9 web apps (manacore, clock, chat,
  manadeck, calendar, zitare, contacts, picture, todo)
- Add proper ARIA attributes (role, tabindex, aria-label) to interactive elements
- Add onkeydown handlers alongside onclick for keyboard accessibility
- Add svelte-ignore comments for intentional patterns (modals, dropdowns)
- Update svelte-check threshold from error to warning in pre-commit hook
- Fix script compatibility for bash 3.x (remove associative arrays)
- Add comprehensive documentation for svelte-check patterns and fixes

All web apps now pass svelte-check with 0 errors and 0 warnings.
Pre-commit hooks will block any future commits with warnings.

packages/shared-ui/src/context-menu/ContextMenu.svelte

@@ -86,7 +86,6 @@
 
 {#if visible}
 	<!-- Backdrop to block clicks on elements behind -->
-	<!-- svelte-ignore a11y_no_static_element_interactions -->
 	<div
 		class="context-menu-backdrop"
 		onpointerdown={(e) => {
@@ -104,9 +103,17 @@
 			e.stopPropagation();
 			onClose();
 		}}
+		onkeydown={(e) => {
+			if (e.key === 'Escape' || e.key === 'Enter' || e.key === ' ') {
+				e.preventDefault();
+				e.stopPropagation();
+				onClose();
+			}
+		}}
+		role="presentation"
+		aria-hidden="true"
 	></div>
 
-	<!-- svelte-ignore a11y_no_noninteractive_element_interactions -->
 	<div
 		bind:this={menuElement}
 		class="context-menu"