build: add tokens studio cli as dev dependency of eds-tokens

Installs @tokens-studio/studio-cli 0.1.7 and approves its postinstall
binary download in onlyBuiltDependencies, so the setup described in
documentation/agent-instructions/TOKENS_STUDIO.md works from this
branch onwards.

Author: pomfrida

packages/eds-tokens/package.json

@@ -100,6 +100,7 @@
     "@rollup/plugin-babel": "^7.1.0",
     "@rollup/plugin-commonjs": "^29.0.3",
     "@rollup/plugin-node-resolve": "^16.0.3",
+    "@tokens-studio/studio-cli": "^0.1.7",
     "@types/node": "^25.5.2",
     "copyfiles": "^2.4.1",
     "lightningcss-cli": "^1.32.0",