Fix observer reports: charts, filtering, project preview, dashboard stats

- Rewrite diversity metrics: horizontal bar charts for ocean issues and
  geographic distribution (replaces unreadable vertical/donut charts)
- Rewrite juror score heatmap: expandable table with score distribution
- Rewrite juror consistency: horizontal bar visual with juror names
- Merge filtering tabs into single screening view with per-project
  AI reasoning and expandable rows
- Add project preview dialog for juror performance table
- Fix status breakdown for evaluation rounds (Fully/Partially/Not Reviewed)
- Show active round name instead of count on observer dashboard
- Move Global tab to last position, default to first round-specific tab
- Add 4-card stats layout for evaluation with reviews/project ratio
- Fix oceanIssue field (singular) and remove non-existent aiSummary

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

src/app/(observer)/observer/reports/page.tsx

@@ -129,7 +129,7 @@ function ReportsPageContent() {
   const searchParams = useSearchParams()
   const roundFromUrl = searchParams.get('round')
   const [selectedValue, setSelectedValue] = useState<string | null>(roundFromUrl)
-  const [activeTab, setActiveTab] = useState('global')
+  const [activeTab, setActiveTab] = useState<string | null>(null)
 
   const { data: programs, isLoading: stagesLoading } = trpc.program.list.useQuery({ includeStages: true })
 
@@ -150,9 +150,9 @@ function ReportsPageContent() {
     }
   }, [stages.length, selectedValue])
 
-  // Reset to global tab when round selection changes
+  // Reset to first round-specific tab when round selection changes
   useEffect(() => {
-    setActiveTab('global')
+    setActiveTab(null)
   }, [selectedValue])
 
   const isAllRounds = selectedValue?.startsWith('all:')
@@ -167,8 +167,8 @@ function ReportsPageContent() {
     : getRoundTabs(roundType)
 
   const allTabs: TabDef[] = [
-    { value: 'global', label: 'Global', icon: Globe },
     ...roundSpecificTabs,
+    { value: 'global', label: 'Global', icon: Globe },
   ]
 
   return (
@@ -206,7 +206,7 @@ function ReportsPageContent() {
       </div>
 
       {selectedValue && (
-        <Tabs value={activeTab} onValueChange={setActiveTab} className="space-y-6">
+        <Tabs value={activeTab ?? allTabs[0]?.value ?? 'global'} onValueChange={setActiveTab} className="space-y-6">
           <TabsList>
             {allTabs.map((tab) => (
               <TabsTrigger key={tab.value} value={tab.value} className="gap-2">