fix: rename 'In Session' to 'Total Time' for clarity

Makes it clear the timer is an aggregate of all sessions today,
not just the current one.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/sidebar/SidebarStatsBar.tsx

@@ -80,12 +80,12 @@ export function SidebarStatsBar({ resolved, active, completedMinutes, activeSess
       <div className="flex-1 rounded-md bg-[rgba(255,255,255,0.02)] px-1 py-1.5 text-center">
         <div
           className="font-label text-sm font-semibold leading-none text-muted-foreground"
-          aria-label={`${formatDuration(totalSeconds)} in session today`}
+          aria-label={`${formatDuration(totalSeconds)} total session time today`}
         >
           {formatDuration(totalSeconds)}
         </div>
         <div className="mt-1 font-label text-[7px] uppercase tracking-[0.1em] text-[#3d4350]">
-          In Session
+          Total Time
         </div>
       </div>
     </div>