feat: router.back() navigation, read-only evaluation view, auth audit logging

- Convert all Back buttons platform-wide (38 files) to use router.back()
  for natural browser-back behavior regardless of entry point
- Add read-only view for submitted evaluations in closed rounds with
  blue banner, disabled inputs, and contextual back navigation
- Add auth audit logs: MAGIC_LINK_SENT, PASSWORD_RESET_LINK_CLICKED,
  PASSWORD_RESET_LINK_EXPIRED, PASSWORD_RESET_LINK_INVALID
- Learning Hub links navigate in same window for all roles
- Update settings descriptions to reflect all-user scope

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

src/components/admin/semi-finalists-content.tsx

@@ -3,6 +3,7 @@
 import { useState, useMemo } from 'react'
 import Link from 'next/link'
 import type { Route } from 'next'
+import { useRouter } from 'next/navigation'
 import { trpc } from '@/lib/trpc/client'
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { Input } from '@/components/ui/input'
@@ -55,6 +56,7 @@ type SemiFinalistsContentProps = {
 }
 
 export function SemiFinalistsContent({ editionId }: SemiFinalistsContentProps) {
+  const router = useRouter()
   const { data, isLoading } = trpc.dashboard.getSemiFinalistDetail.useQuery(
     { editionId },
     { enabled: !!editionId }
@@ -116,11 +118,9 @@ export function SemiFinalistsContent({ editionId }: SemiFinalistsContentProps) {
       {/* Header */}
       <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
         <div className="flex items-center gap-3">
-          <Link href={'/admin' as Route}>
-            <Button variant="ghost" size="icon" className="h-8 w-8">
-              <ArrowLeft className="h-4 w-4" />
-            </Button>
-          </Link>
+          <Button variant="ghost" size="icon" className="h-8 w-8" onClick={() => router.back()}>
+            <ArrowLeft className="h-4 w-4" />
+          </Button>
           <div>
             <h1 className="text-xl font-bold tracking-tight md:text-2xl">
               Semi-Finalists

src/components/layouts/role-nav.tsx

@@ -142,8 +142,6 @@ export function RoleNav({ navigation, roleName, user, basePath, statusBadge, edi
                   <a
                     key={item.name}
                     href={item.href}
-                    target="_blank"
-                    rel="noopener noreferrer"
                     className={className}
                     onClick={() => logNavClick.mutate({ url: item.href })}
                   >
@@ -291,8 +289,6 @@ export function RoleNav({ navigation, roleName, user, basePath, statusBadge, edi
                     <a
                       key={item.name}
                       href={item.href}
-                      target="_blank"
-                      rel="noopener noreferrer"
                       onClick={() => { logNavClick.mutate({ url: item.href }); setIsMobileMenuOpen(false) }}
                       className={className}
                     >

src/components/observer/observer-project-detail.tsx

@@ -2,6 +2,7 @@
 
 import Link from 'next/link'
 import type { Route } from 'next'
+import { useRouter } from 'next/navigation'
 import { trpc } from '@/lib/trpc/client'
 import {
   Card,
@@ -43,6 +44,7 @@ import {
 import { cn, formatDate, formatDateOnly } from '@/lib/utils'
 
 export function ObserverProjectDetail({ projectId }: { projectId: string }) {
+  const router = useRouter()
   const { data, isLoading } = trpc.analytics.getProjectDetail.useQuery(
     { id: projectId },
     { refetchInterval: 30_000 },
@@ -78,8 +80,8 @@ export function ObserverProjectDetail({ projectId }: { projectId: string }) {
           <CardContent className="flex flex-col items-center justify-center py-12 text-center">
             <AlertCircle className="h-12 w-12 text-destructive/50" />
             <p className="mt-2 font-medium">Project Not Found</p>
-            <Button asChild className="mt-4">
-              <Link href={'/observer' as Route}>Back to Dashboard</Link>
+            <Button className="mt-4" onClick={() => router.back()}>
+              Back
             </Button>
           </CardContent>
         </Card>
@@ -152,11 +154,9 @@ export function ObserverProjectDetail({ projectId }: { projectId: string }) {
   return (
     <div className="space-y-6">
       {/* Back button */}
-      <Button variant="ghost" size="sm" className="gap-1.5 -ml-2 text-muted-foreground" asChild>
-        <Link href={'/observer/projects' as Route}>
-          <ArrowLeft className="h-3.5 w-3.5" />
-          Back to Projects
-        </Link>
+      <Button variant="ghost" size="sm" className="gap-1.5 -ml-2 text-muted-foreground" onClick={() => router.back()}>
+        <ArrowLeft className="h-3.5 w-3.5" />
+        Back
       </Button>
 
       {/* Project Header */}

src/components/settings/settings-content.tsx

@@ -927,13 +927,13 @@ function PlatformFeaturesSection({ settings }: { settings: Record<string, string
         <Label className="text-sm font-medium">Learning Hub</Label>
         <SettingToggle
           label="Use External Learning Hub"
-          description="When enabled, jury and mentor navigation links will open the external URL instead of the built-in Learning Hub"
+          description="When enabled, all user navigation links (jury, mentor, applicant) will redirect to the external URL instead of the built-in Learning Hub"
           settingKey="learning_hub_external"
           value={settings.learning_hub_external || 'false'}
         />
         <SettingInput
           label="External URL"
-          description="The URL to redirect jury and mentor users to (e.g. Google Drive, Notion, etc.)"
+          description="The URL to redirect users to (e.g. Google Drive, Notion, etc.)"
           settingKey="learning_hub_external_url"
           value={settings.learning_hub_external_url || ''}
         />