Issue 32: Add ISO8601 timestamp to date display title attribute

Add ISO8601 (UTC) formatted timestamp as a native browser tooltip on all
date displays. This allows users to easily copy the exact timestamp while
still seeing human-readable relative times and formatted dates in the
custom tooltip.

Fixes #32

Author: WilliamZhang9

packages/web/src/app/[domain]/components/DisplayDate.tsx

@@ -19,6 +19,9 @@ interface DisplayDateProps {
 }
 
 export const DisplayDate = ({ date, className }: DisplayDateProps) => {
+    // Format date in ISO8601 (UTC) format
+    const iso8601Date = date.toISOString()
+    
     return (
         <TooltipProvider>
             <Tooltip>
@@ -28,7 +31,7 @@ export const DisplayDate = ({ date, className }: DisplayDateProps) => {
                     </span>
                 </TooltipTrigger>
                 <TooltipContent>
-                    <p>{formatFullDate(date)}</p>
+                    <p>{iso8601Date}</p>
                 </TooltipContent>
             </Tooltip>
         </TooltipProvider>