♿️ feat: fix accessibility warnings, PWA icons, and form field attributes

- add DialogDescription (sr-only) to EventDialog to satisfy Radix UI
  aria-describedby requirement and silence the React console warning
- add htmlFor/id pairing to the all-day checkbox label in EventDialog
- add id and name attributes to all raw form fields (textarea, checkbox)
  in event-dialog to resolve biome a11y lint warnings (4 fields fixed)
- add name attribute to hidden file inputs in image-picker and ics-file-picker
- generate public/icon-192x192.png and public/icon-512x512.png so the PWA
  manifest no longer returns 404 for the app icons

src/components/image-picker.tsx

@@ -42,6 +42,7 @@ export function ImagePicker({
 			<input
 				ref={fileInputRef}
 				type="file"
+				name="image-upload"
 				accept="image/png,image/jpeg,image/webp"
 				onChange={handleFileChange}
 				className="hidden"