fix(PRI-564): add eslint/prettier/typescript as direct devDeps

pnpm strict isolation (-frozen-lockfile) only exposes binaries from direct
devDependencies. eslint, prettier, and typescript were transitive peers of
@kinvolk/headlamp-plugin and not accessible in CI.

- eslint: ^8.57.1
- prettier: ^3.0.0
- typescript: ^5.6.2

package.json

@@ -36,10 +36,13 @@
     "@testing-library/jest-dom": "^6.4.8",
     "@testing-library/react": "^16.0.0",
     "@testing-library/user-event": "^14.5.2",
+    "eslint": "^8.57.1",
     "jsdom": "^24.0.0",
+    "prettier": "^3.0.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^5.3.0",
+    "typescript": "^5.6.2",
     "vitest": "^3.0.5"
   },
   "overrides": {