feat(ui): unify overlay animations and trim tooltip delays

Use base-ui's transition-status pattern (data-starting-style /
data-ending-style) for Dialog, DropdownMenu, Select, Tooltip and Popover
so open/close animate consistently at 150ms ease-out without flicker.
Wrap dialog popups in a centered flex container so the scale animation
no longer fights with translate-based positioning, and switch
PendingChangesBar to a real Popover so it actually animates closed.

Convert ScheduledTaskEditorDialog from raw Radix to the shared Dialog
wrapper, give ScheduledTasksDialog a stable min-height to prevent layout
shift mid-animation, and reset NewWorktreeDialog form state on open
instead of close so fields don't empty during the close transition.

Drop tooltip delay from 700ms to 300ms globally and remove all
per-component overrides except the model/variant/agent selectors in the
chat input (600ms).

packages/ui/src/components/chat/TurnChangedFilesDropdown.tsx

@@ -84,7 +84,7 @@ export const TurnChangedFilesDropdown: React.FC<TurnChangedFilesDropdownProps> =
 
     return (
         <Popover.Root open={isExpanded} onOpenChange={setIsExpanded}>
-            <Tooltip delayDuration={300}>
+            <Tooltip>
                 <TooltipTrigger asChild>
                     <Popover.Trigger
                         render={
@@ -113,7 +113,7 @@ export const TurnChangedFilesDropdown: React.FC<TurnChangedFilesDropdownProps> =
                 <Popover.Positioner side="top" align="start" sideOffset={4} collisionPadding={8}>
                     <Popover.Popup
                         style={changedFilesPopoverStyle}
-                        className={changedFilesPopoverClassName}
+                        className={`${changedFilesPopoverClassName} transition-all duration-150 ease-out data-[starting-style]:opacity-0 data-[starting-style]:scale-95 data-[ending-style]:opacity-0 data-[ending-style]:scale-95`}
                     >
                         <ChangedFilesList
                             files={changedFiles}