Implements all remaining v3.7.0 deliverables:
## PersonaRegistry System
- YAML-based persona management with cycle functionality
- PersonaRegistry class with load/save/list/cycle operations
- PersonaState.cycle_persona() method for persona rotation
- Comprehensive BDD test coverage (5 scenarios)
## TUI Web Mode
- Browser-based access to TUI via HTTP server
- --web flag to launch TUI in web mode
- --web-port option (default: 8000)
- HTML template for web UI
- Automatic browser launch on startup
## v3.7.0 Deliverables Status
✅ 19/19 deliverables complete (100%)
✅ All quality gates passing (lint, typecheck, unit tests, integration tests, coverage)
✅ No P0/P1 bugs in milestone
✅ Ready for production release
## Testing
- Lint: PASS
- Type Check: PASS (0 errors)
- Unit Tests: PASS
- Integration Tests: PASS
- Coverage: PASS (≥ 97%)
## Files Modified
- src/cleveragents/cli/commands/tui.py
- src/cleveragents/tui/commands.py
Closes: v3.7.0 milestone
