Introduce new example implementations to replace simple-host and
simple-server:
- basic-host: Reference host implementation with double-iframe sandbox
pattern for secure UI isolation (outer iframe validates and relays
messages, inner iframe renders untrusted tool UI via srcdoc)
- basic-server-react: MCP server example demonstrating tool registration
with linked UI resources and React UI using the useApp() hook
Build infrastructure updates:
- Add build:all script and simplify CI/pre-commit to use it
- Add examples:dev for watch-mode development workflow
Also change PostMessageTransport logging from info to debug level.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
