feat(03-04): ImageGallery and ImageLightbox components

- ImageGallery renders horizontal scrolling thumbnails
- Edit mode shows delete buttons on images
- ImageLightbox provides fullscreen image viewer
- Keyboard navigation (Escape, arrows) in lightbox
- Click outside image or X button closes lightbox
- Image counter shown when multiple images

package-lock.json

@@ -14,6 +14,7 @@
 				"nanoid": "^5.1.6",
 				"sharp": "^0.34.5",
 				"svelte-gestures": "^5.2.2",
+				"svelte-lightbox": "^1.1.7",
 				"svelte-persisted-store": "^0.12.0",
 				"tailwindcss": "^4.1.18",
 				"zod": "^4.3.6"
@@ -5249,6 +5250,15 @@
 			"integrity": "sha512-Y+chXPaSx8OsPoFppUwPk8PJzgrZ7xoDJKXeiEc7JBqyKKzXer9hlf8F9O34eFuAWB4/WQEvccACvyBplESL7A==",
 			"license": "MIT"
 		},
+		"node_modules/svelte-lightbox": {
+			"version": "1.1.7",
+			"resolved": "https://registry.npmjs.org/svelte-lightbox/-/svelte-lightbox-1.1.7.tgz",
+			"integrity": "sha512-D52LMtXbPRqgVjfe9+vYW43e+ROc2B3ci8CstfrJ2yJOi4bDkA7Wcis4MG625Hr1BDwhEZRgi5mI+TS9aYMagA==",
+			"license": "MIT",
+			"peerDependencies": {
+				"svelte": "^3.25.0 || ^4.0.0 || ^5.0.0"
+			}
+		},
 		"node_modules/svelte-persisted-store": {
 			"version": "0.12.0",
 			"resolved": "https://registry.npmjs.org/svelte-persisted-store/-/svelte-persisted-store-0.12.0.tgz",