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/TimelineDialog.tsx

@@ -145,7 +145,7 @@ export const TimelineDialog: React.FC<TimelineDialogProps> = ({
                                         </span>
 
                                         <div className="hidden group-hover:flex gap-1">
-                                            <Tooltip delayDuration={1000}>
+                                            <Tooltip>
                                                 <TooltipTrigger asChild>
                                                     <button
                                                         type="button"
@@ -162,7 +162,7 @@ export const TimelineDialog: React.FC<TimelineDialogProps> = ({
                                                 <TooltipContent sideOffset={6}>{t('chat.timeline.actions.revertFromHere')}</TooltipContent>
                                             </Tooltip>
 
-                                            <Tooltip delayDuration={1000}>
+                                            <Tooltip>
                                                 <TooltipTrigger asChild>
                                                     <button
                                                         type="button"