[ci skip] Add one-command setup scripts to k8s-portal

- Add /setup/script?os=mac and /setup/script?os=linux endpoints
- Scripts install kubectl, kubelogin, write kubeconfig, update shell rc
- Unprotected ingress for /setup/script (curl-able without auth)
- Fix kubeconfig to include --oidc-extra-scope for email/profile/groups

modules/kubernetes/k8s-portal/files/.gitignore

@@ -0,0 +1,23 @@
+node_modules
+
+# Output
+.output
+.vercel
+.netlify
+.wrangler
+/.svelte-kit
+/build
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Env
+.env
+.env.*
+!.env.example
+!.env.test
+
+# Vite
+vite.config.js.timestamp-*
+vite.config.ts.timestamp-*