feat: rich content rendering with structured Notion block parsing

feat: arrow key navigation — right to enter detail, left to go back

feat: sub-task support — board shows root tasks, detail expands children

feat: multi-owner assign menu and refresh owner persistence

fix: date-based sprint detection, mouse UX, and cleanup

feat: bigger loading animation, error handling, and UX improvements

feat: add mouse support (click, double-click, scroll)

UX: dynamic owner pane width, g/G nav, sprint dates, active owner title

Migrate to ratatui_ruby with dual-pane layout and animated loading

Add sprint navigation, owner filtering, detail scrolling, and live search

🌙 Initial commit - nox Notion TUI