fix: pipeline progress, message variables, jury invite flow, accept-invite UX

- Pipeline: SUBMISSION rounds count IN_PROGRESS + COMPLETED for progress %
- Round engine: remove phantom SubmissionFileRequirement check blocking auto-transition
- Messages: implement {{userName}}, {{projectName}}, {{roundName}}, {{programName}}, {{deadline}} substitution
- Email preview: show greeting, CTA button, and footer matching actual sent email
- Message composer: add green dot indicator for active rounds in round selector
- User create: generate invite token atomically (prevents stuck INVITED state on email failure)
- Jury invites: use jury-specific email template mentioning round context
- Bulk invite: animated progress bar, batch size hint, success/failure counts
- Accept invite: distinguish server errors (retry button) from expired tokens (redirect)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/(auth)/accept-invite/page.tsx

@@ -11,7 +11,7 @@ import {
   CardHeader,
   CardTitle,
 } from '@/components/ui/card'
-import { Loader2, CheckCircle2, AlertCircle, XCircle, Clock } from 'lucide-react'
+import { Loader2, CheckCircle2, AlertCircle, XCircle, Clock, RefreshCw } from 'lucide-react'
 import Image from 'next/image'
 import { trpc } from '@/lib/trpc/client'
 import { AnimatedCard } from '@/components/shared/animated-container'
@@ -64,6 +64,48 @@ function ErrorRedirectCard({
   )
 }
 
+function NetworkErrorCard({ onRetry, isRetrying }: { onRetry: () => void; isRetrying: boolean }) {
+  return (
+    <AnimatedCard>
+      <Card className="w-full max-w-md overflow-hidden">
+        <div className="h-1 w-full bg-gradient-to-r from-brand-blue via-brand-teal to-brand-blue" />
+        <CardHeader className="text-center">
+          <div className="mx-auto mb-4 flex h-12 w-12 items-center justify-center rounded-2xl bg-gray-100">
+            <AlertCircle className="h-6 w-6 text-amber-600" />
+          </div>
+          <CardTitle className="text-xl">Something Went Wrong</CardTitle>
+          <CardDescription className="text-base">
+            We couldn&apos;t verify your invitation due to a server or network issue.
+            This is not a problem with your invitation link.
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="space-y-3">
+          <Button
+            className="w-full"
+            onClick={onRetry}
+            disabled={isRetrying}
+          >
+            {isRetrying ? (
+              <>
+                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+                Retrying...
+              </>
+            ) : (
+              <>
+                <RefreshCw className="mr-2 h-4 w-4" />
+                Try Again
+              </>
+            )}
+          </Button>
+          <p className="text-xs text-center text-muted-foreground">
+            If the problem persists, please contact your administrator.
+          </p>
+        </CardContent>
+      </Card>
+    </AnimatedCard>
+  )
+}
+
 function AcceptInviteContent() {
   const [state, setState] = useState<InviteState>('loading')
   const [errorType, setErrorType] = useState<string | null>(null)
@@ -72,7 +114,7 @@ function AcceptInviteContent() {
   const router = useRouter()
   const token = searchParams.get('token') || ''
 
-  const { data, isLoading, error } = trpc.user.validateInviteToken.useQuery(
+  const { data, isLoading, error, refetch, isRefetching } = trpc.user.validateInviteToken.useQuery(
     { token },
     { enabled: !!token, retry: false }
   )
@@ -197,8 +239,23 @@ function AcceptInviteContent() {
     )
   }
 
-  // Error state — auto-redirect to login after 4 seconds for known errors
+  // Error state
   if (state === 'error') {
+    // Network/server errors get a retry button instead of auto-redirect
+    if (errorType === 'NETWORK_ERROR') {
+      return (
+        <NetworkErrorCard
+          onRetry={() => {
+            setState('loading')
+            setErrorType(null)
+            refetch()
+          }}
+          isRetrying={isRefetching}
+        />
+      )
+    }
+
+    // Token validation errors auto-redirect to login after 4 seconds
     const errorContent = getErrorContent()
     const redirectTarget = errorContent.redirect || '/login'