fix: refine nested flow conditionals and ensure router methods and routes are fully parsed
fix: improve docstrings, typing, and logging coverage across all events
feat: update flow.plot feature with new UI enhancements
chore: apply Ruff linting, reorganize imports, and remove deprecated utilities/files
chore: split constants and utils, clean JS comments, and add typing for linters
tests: strengthen test coverage for flow execution paths and router logic
