Screens and navigation

The launch gate sends first runs to welcome and onboarding, and returning users straight to Today. Five tabs — Today, Habits, Tasks, Stats, Profile — share one swipeable pager with a floating bar; detail screens for habits, tasks, statistics, history, and achievements open as stack cards on top. Search and settings are stack screens too, reachable from the tabs.

Every route literal lives in a checked route table, so renames break the build instead of the navigation.

Sources: src/app/_layout.tsx, src/app/(tabs)/_layout.tsx, src/utils/routes.ts (documented at commit 99a2c3d)