Fix invisible bars in the 14-day tickets chart

The row container used items-end without an explicit height, so each
day column had an auto (indefinite) cross-axis size. Percentage
heights don't resolve against an indefinite-height ancestor, so every
bar collapsed to zero height regardless of its data — only the
hover-tooltip count was visible, not the bar itself. Removing
items-end lets columns stretch to the parent's fixed h-32, giving the
inner bar's height percentage something concrete to resolve against.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012o9j9RezxbZVKQMrB7oRLY

src/app/(admin)/stats/charts.tsx

@@ -54,7 +54,7 @@ export function DailyBarChart({ data }: { data: { label: string; count: number }
 
   return (
     <div>
-      <div className="flex h-32 items-end gap-1 border-b border-border pb-0.5">
+      <div className="flex h-32 gap-1 border-b border-border pb-0.5">
         {data.map((d, i) => (
           <div key={i} className="group relative flex flex-1 flex-col items-center justify-end" title={`${d.label}: ${d.count}`}>
             {d.count > 0 && (