feat: new workspace screen with sticky search combobox design

- Replace workspace setup dialog with full-screen new workspace route
- Restyle Combobox SearchInput to match CombinedModelSelector Level 2 design:
  borderless sticky search bar above scroll area instead of inline bordered box
- CombinedModelSelector now uses shared SearchInput, removing duplicate ProviderSearchInput
- Fix TooltipTrigger children type to accept render functions (remove PropsWithChildren wrapper)
- Fix empty rightControls View causing gap between dictation and send buttons
- Add branch picker with searchable Combobox and GitBranch icons
- Muted icon buttons (attachment, dictation, voice mode) that brighten on hover

packages/app/src/components/ui/tooltip.tsx

@@ -246,12 +246,11 @@ export function TooltipTrigger({
   asChild = false,
   triggerRefProp = "ref",
   ...props
-}: PropsWithChildren<
-  PressableProps & {
+}: PressableProps & {
     asChild?: boolean;
     triggerRefProp?: string;
   }
->): ReactElement {
+): ReactElement {
   const ctx = useTooltipContext("TooltipTrigger");
   const openTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);