- Implement dispatcher allowing access to web, tui, ai, ag, prov-gen via single entry point
- Add 5 new subcommands with 3-line help format (description + usage + options)
- Update CLI help text with backend examples and quick start
- Update README.md with unified command interface section
- Maintain backward compatibility with direct binary invocation
- All backends now accessible: typedialog web/tui/ai/ag/prov-gen
✓ Tests pass, no compiler warnings
