feat: integrate OIDC token exchange in GitHub Action

- Add setupGitHubInstallationToken utility for OIDC token generation
- Implement automatic token exchange with Pullfrog API endpoint
- Add support for multiple authentication methods (input, env, OIDC)
- Create setup utilities for test repository management
- Update action entry point to handle new token flow
- Add environment variable documentation for API key
- Remove large bundled dependencies and optimize build
- Support both development and production token workflows

action.yml

@@ -10,6 +10,12 @@ inputs:
   anthropic_api_key:
     description: "Anthropic API key for Claude Code authentication"
     required: false
+  github_token:
+    description: "GitHub token for repository access"
+    required: false
+  github_installation_token:
+    description: "GitHub App installation token"
+    required: false
 
 runs:
   using: "node20"