Remove the full welcome tour (Welcome, AddTask, DeleteTask, Projects,
Sync, IssueProviders, ProductivityHelper, FinalCongrats, StartTourAgain)
and keep only the KeyboardNav tour, triggered from the Help menu.
- Delete ShepherdComponent (auto-start on load)
- Strip shepherd-steps.const.ts to KeyboardNav steps only
- Simplify ShepherdService with _initPromise guard and fresh tour on re-open
- Remove 3 tour menu items from Help menu, keep keyboard tour
- Remove waitForEl/waitForElObs$ helpers (unused by KeyboardNav)
- Delete e2e/utils/tour-helpers.ts and all tour dismissal calls
- Clean up stale tour comments across e2e tests
- Fix pre-existing build error: add isFinishDayEnabled to AppFeaturesConfig
type, defaults, form toggle, component signal, and translations