build(admin): npm ci instead of bun + arm64-capable lockfile for multi-arch

- Dockerfile: bun install -> npm ci (bun tar-extract unstable under qemu arm64)
- pin @hookform/resolvers 5.2.2 (5.7.x forces ajv@8 -> broken npm lockfile)
- package-lock.json regenerated with linux-arm64 native optionals (lightningcss, sharp, tailwindcss-oxide, parcel/watcher)
- runtime CMD stays node server.js (bun not installed in runner image)

admin-next/package.json

@@ -16,7 +16,7 @@
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
-    "@hookform/resolvers": "^5.1.1",
+    "@hookform/resolvers": "5.2.2",
     "@mdxeditor/editor": "^3.39.1",
     "@prisma/client": "^6.11.1",
     "@radix-ui/react-accordion": "^1.2.11",