feat: add chatloop ralph and next flows

[RexWzh]

Summary

• add chatloop-ralph as a PRD-aware refresh-session loop that creates a new session on each continuation and switches the TUI to that refreshed session
• add chatloop-next as a handoff helper for follow-up tasks so current outputs can be packaged into project-local reference/, memory.md / progress.md can be updated, and PRD.md can be prepared for the next requirement discussion
• improve chatloop diagnostics and docs so /chatloop-project, /chatloop-status, and the current command set clearly explain project resolution, loop mode, and lifecycle state

Testing

• pytest tests/mock-cli-tests/opencode/test_chattool_setup_opencode_basic.py tests/mock-cli-tests/setup/test_chattool_setup_workspace_mock_basic.py tests/cli-tests/setup/test_chattool_setup_workspace_real_basic.py