- Replace 5-tab layout with 4 tabs: Dashboard, Timer, Entries, Settings
- Dashboard: add Work Time Balance section using /client-targets API, showing
per-client weekly progress bar, overtime/undertime label and expandable week breakdown
- Time Entries: replace flat list with UICalendarView month grid; tap a day to see
that day's entries; add filter sheet (date range, project, client); new
TimeEntryDetailSheet for creating and editing entries; duration shown as Xh Ymin
- Settings tab: user info header, navigation to Clients and Projects, logout button
- ClientsListView: list with NavigationLink to ClientDetailView
- ClientDetailView: inline client editing + full work time target CRUD (create,
edit, delete target; add/delete balance corrections with date, hours, description)
- ProjectsListView: grouped by client, NavigationLink to ProjectDetailView
- ProjectDetailView: edit name, description, colour, client assignment
- Add ClientTarget, WeekBalance, BalanceCorrection models and APIEndpoints for
/client-targets routes
- Update TimeInterval formatter: add formattedShortDuration (Xh Ymin / Xmin / <1min)
used throughout app; keep formattedDuration for live timer display
