chore(deps): update shiki to v4

Author: have-renovate[bot]

package.json

@@ -90,7 +90,7 @@
     "@types/node": "^24.12.0",
     "lefthook": "^2.1.3",
     "mdsvex": "^0.12.7",
-    "shiki": "^3.23.0",
+    "shiki": "^4.0.2",
     "storybook": "^8.6.18",
     "svelte-check": "^4.4.5",
     "tslib": "^2.8.1",