initial: @a2a/mcp gateway for a2acloud agents

Local MCP server that exposes any number of deployed A2A agents to
Claude Code, Cursor, Windsurf, and other MCP clients. Reuses the
~/.a2a/credentials.json token written by the Python a2a CLI. Adding
or removing agents is a single ~/.a2a/mcp.json edit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,7 @@
+node_modules/
+dist/
+*.log
+*.tsbuildinfo
+.DS_Store
+.env
+.env.local