Make the shell taskbar and app launcher touch-first and customizable

[vatiolibre]

This PR improves the VatioBoard OS shell taskbar and app launcher so they feel more familiar on desktop while staying functional on touch-first devices.

The taskbar now defaults to a Windows-like lower-left docked position, can still be dragged/detached, supports favorites more naturally, and handles crowded mobile layouts without hiding critical controls like login/account. The app launcher now behaves more like a phone home screen with smooth page-card swiping, stable app ordering, touch-friendly context actions, and an arrange mode for drag-to-reorder.

What changed

• Refactored the shell taskbar into a lower-left dockable control with a dedicated drag handle, persisted detached positioning, and redocking when dropped back near the lower-left dock zone.
• Added taskbar favorites support from launcher tiles and from already-open taskbar apps, including drag-to-remove behavior for favorites.
• Improved crowded mobile taskbar behavior with horizontal tray/favorites scrolling, overflow handling, preserved icon shadows, and always-visible account/login access.
• Published taskbar avoidance spacing through shell CSS so route/app UI can avoid being covered by the docked taskbar.
• Updated app-level styles for board, camera map, calculator, energy, player, accel, replay, library, GPS rate, clock, code rain, and activity UI to respect the taskbar/safe-area spacing.
• Reworked the app launcher pages into a horizontal card track with smooth swipe transitions and inert non-active pages.
• Made app launcher order stable by default, added persisted custom launcher ordering, and introduced arrange mode with drag-to-reorder and reset/done controls.
• Restored touch-friendly long-press/context-sheet access for launcher actions like favorite, hide, and arrange.
• Fixed related regressions around app opening, iPhone login visibility, taskbar icon clipping, and stale CI assertions.