feat: Add support for environment protection (scrubbing) (#327)

* feat: Add support for environment variable protection for sandbox

* chore: Update dangerous env var list

* fix: Split profiles for improved environment protection

* fix: pipx sandbox profile separation

* chore: Show sandbox scrub info on error exit

* fix: Code review fixes

* test: Add e2e for sandbox environment scrubbing

sandbox/profiles/yarn.yml

@@ -0,0 +1,20 @@
+name: yarn
+description: Profile for yarn, extending npm-restrictive with yarn environment variables
+inherits: npm-restrictive
+
+package_managers:
+  - yarn
+
+environment:
+  # Yarn berry authenticates via YARN_NPM_AUTH_*. Yarn classic reads .npmrc
+  # with env interpolation and npm_config_* conventions, so the shared npm
+  # auth set is also needed. Sibling tokens (BUN_AUTH_TOKEN) stay scrubbed.
+  allow:
+    - YARN_NPM_AUTH_TOKEN
+    - YARN_NPM_AUTH_IDENT
+    - NPM_TOKEN
+    - NPM_AUTH_TOKEN
+    - NODE_AUTH_TOKEN
+    - npm_config_*
+    - NPM_CONFIG_*
+    - NODE_EXTRA_CA_CERTS