fix: scope observer reports preview dialog to selected round

Threads the active roundId through ProjectPreviewDialog and its two
callers (filtering tabs, expandable juror table). When a round is in
scope, the preview's stats card now matches the per-juror list and
the page-level round selector. The roundId prop is optional so the
component still works in any future caller that lacks round context.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/observer/reports/project-preview-dialog.tsx

@@ -21,6 +21,7 @@ import { scoreGradient } from '@/components/charts/chart-theme'
 
 interface ProjectPreviewDialogProps {
   projectId: string | null
+  roundId?: string
   open: boolean
   onOpenChange: (open: boolean) => void
 }
@@ -38,9 +39,9 @@ function ScorePill({ score }: { score: number }) {
   )
 }
 
-export function ProjectPreviewDialog({ projectId, open, onOpenChange }: ProjectPreviewDialogProps) {
+export function ProjectPreviewDialog({ projectId, roundId, open, onOpenChange }: ProjectPreviewDialogProps) {
   const { data, isLoading } = trpc.analytics.getProjectDetail.useQuery(
-    { id: projectId! },
+    { id: projectId!, roundId },
     { enabled: !!projectId && open },
   )