fix(header): inactive-tab rename actually starts; snappier tab state change

Rename from another tab's menu stored only a boolean that the
session-switch reset effect wiped before the menu finished closing, so
the tab activated but rename never began. The pending rename now
carries the target session id and begins exactly when that session
becomes active (whether the menu closes before or after the switch),
without the reset effect cancelling it — and without an in-flight
rename being cancelled by unrelated re-renders. Tab background/text
state changes animate at 75ms so activation reads immediate.

packages/ui/src/components/layout/SessionTabsStrip.tsx

@@ -222,10 +222,11 @@ const SessionTabItem: React.FC<{
                   data-controls-open={overlayVisible ? 'true' : 'false'}
                   className={cn(
                     'session-tab group/session-tab relative flex h-7 w-full min-w-0 select-none items-center rounded-md px-2',
+                    'transition-colors duration-75',
                     isActive
                       ? 'bg-interactive-selection'
                       : cn(
-                        'cursor-pointer text-muted-foreground transition-colors duration-150 hover:bg-interactive-hover hover:text-foreground',
+                        'cursor-pointer text-muted-foreground hover:bg-interactive-hover hover:text-foreground',
                         overlayVisible && 'bg-interactive-hover text-foreground',
                       ),
                   )}