feat: integrate Claude Code SDK to replace process spawning (#327)

* feat: integrate Claude Code SDK to replace process spawning

- Add @anthropic-ai/claude-code dependency to base-action
- Replace mkfifo/cat process spawning with direct SDK usage
- Remove global Claude Code installation from action.yml files
- Maintain full compatibility with existing options
- Add comprehensive tests for SDK integration

This change makes the implementation cleaner and more reliable by
eliminating the complexity of managing child processes and named pipes.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: add debugging and bun executable for Claude Code SDK

- Add stderr handler to capture CLI errors
- Explicitly set bun as the executable for the SDK
- This should help diagnose why the CLI is exiting with code 1

* fix: extract mcpServers from parsed MCP config

The SDK expects just the servers object, not the wrapper object with mcpServers property.

* tsc

---------

Co-authored-by: Claude <noreply@anthropic.com>

package.json

@@ -12,6 +12,7 @@
   "dependencies": {
     "@actions/core": "^1.10.1",
     "@actions/github": "^6.0.1",
+    "@anthropic-ai/claude-code": "1.0.57",
     "@modelcontextprotocol/sdk": "^1.11.0",
     "@octokit/graphql": "^8.2.2",
     "@octokit/rest": "^21.1.1",