手机上画面清晰了，还有了摇杆

变更

• Crisp mobile layout, virtual joystick and equipment slot icons

  Switch the window stretch from "viewport" to "canvas_items" + "expand" (base 640x420, nearest filter kept, clear color = game background), so text renders at device resolution and 20:9 phones get no black bars. New client/ui/screen.gd anchors everything to the visible area: the room arena is centered above the bar via the root canvas transform, the city camera uses the full width, the bottom bar sits at the bottom of the display safe area with its frame spanning edge to edge, UI layers are centered (panels never under the bar, status strip and toasts at the top) and modal dims cover the side bands. The safe area can be simulated with --safe-inset=l,t,r,b. The 1x/1.25x/1.5x interface scale is enabled again: it scales the bar and UI layers, clamped to what fits the safe area, so it never cuts the HUD (on 16:10 windows it stays 1x; on 20:9 the bar grows). Optional virtual joystick in rooms (Options toggle, on by default only on touch devices): hold on the left half of the arena and drag to move the team like WASD, release to stop; a tap without dragging is still click-to-move, and the skill row, cards and bar keep priority. It tracks the finger index, so another finger can still use skills. Equipment slots in the Character panel get Kenney 1-Bit Pack (CC0) icons, registered in CREDITS.md. tap_test now converts logical to window coordinates (works at any --resolution) and covers the joystick. Marks items 29, 31 and 35 in docs/fluxo-do-cliente.md.