feat: show active timer on dashboard homepage with clock-out button

Adds a banner below the page header when a timer is running: shows
description, client, elapsed time (live), a Stop button that auto-links
to the latest invoice, and a Details link to the time clock page.
Query is prefetched server-side so the widget is instant on load.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/dashboard/page.tsx

@@ -492,6 +492,7 @@ function CardSkeleton() {
 }
 
 import { DashboardPageHeader } from "~/components/layout/page-header";
+import { ActiveTimerWidget } from "~/app/dashboard/_components/active-timer-widget";
 
 // ... imports
 
@@ -503,6 +504,7 @@ export default async function DashboardPage() {
 
   // Fetch stats centrally
   const stats = await api.dashboard.getStats();
+  void api.timeEntries.getRunning.prefetch();
 
   return (
     <div className="page-enter space-y-6">
@@ -511,6 +513,10 @@ export default async function DashboardPage() {
         description="Here's what's happening with your business today"
       />
 
+      <HydrateClient>
+        <ActiveTimerWidget />
+      </HydrateClient>
+
       <HydrateClient>
         <Suspense fallback={<StatsSkeleton />}>
           <DashboardStats stats={stats} />