chore(plugin-dev): add @objectstack/rest to devDependencies

Address code review feedback: ensure all dynamically imported
optional peer dependencies are available during development.

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/plugins/plugin-dev/package.json

@@ -42,6 +42,7 @@
     "@objectstack/runtime": "workspace:*",
     "@objectstack/plugin-auth": "workspace:*",
     "@objectstack/plugin-hono-server": "workspace:*",
+    "@objectstack/rest": "workspace:*",
     "@types/node": "^25.2.2",
     "typescript": "^5.0.0",
     "vitest": "^4.0.18"