Platform review round 2: audit logging migration, nav unification, DB indexes, and UI polish

- Migrate ~41 inline audit log calls to shared logAudit() utility across all routers
- Add transaction-aware prisma parameter to logAudit() for atomic operations
- Unify jury/mentor/observer navigation into shared RoleNav component
- Add composite DB indexes (Evaluation, GracePeriod, AuditLog) for query performance
- Fix profile page: consolidate dual save buttons, proper useEffect initialization
- Enhance auth error page with MOPC branding and navigation
- Improve observer dashboard with prominent read-only badge
- Fix DI-3: fetch projects before bulk status update for accurate notifications
- Remove unused aiBoost field from smart-assignment scoring
- Add shared image-upload utility and structured logger module

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

src/app/(auth)/error/page.tsx

@@ -4,6 +4,7 @@ import { useSearchParams } from 'next/navigation'
 import Link from 'next/link'
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { Button } from '@/components/ui/button'
+import { Logo } from '@/components/shared/logo'
 import { AlertCircle } from 'lucide-react'
 
 const errorMessages: Record<string, string> = {
@@ -21,16 +22,22 @@ export default function AuthErrorPage() {
   return (
     <Card className="w-full max-w-md">
       <CardHeader className="text-center">
-        <div className="mx-auto mb-4 flex h-12 w-12 items-center justify-center rounded-full bg-destructive/10">
+        <div className="mx-auto mb-4">
+          <Logo variant="small" />
+        </div>
+        <div className="mx-auto mb-2 flex h-12 w-12 items-center justify-center rounded-full bg-destructive/10">
           <AlertCircle className="h-6 w-6 text-destructive" />
         </div>
         <CardTitle className="text-xl">Authentication Error</CardTitle>
       </CardHeader>
       <CardContent className="space-y-4 text-center">
         <p className="text-muted-foreground">{message}</p>
-        <div className="border-t pt-4">
+        <div className="flex gap-3 justify-center border-t pt-4">
           <Button asChild>
-            <Link href="/login">Try again</Link>
+            <Link href="/login">Return to Login</Link>
+          </Button>
+          <Button variant="outline" asChild>
+            <Link href="/">Home</Link>
           </Button>
         </div>
       </CardContent>

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

@@ -67,19 +67,24 @@ async function ObserverDashboardContent() {
   return (
     <>
       {/* Observer Notice */}
-      <Card className="border-blue-200 bg-blue-50 dark:border-blue-900 dark:bg-blue-950/30">
-        <CardContent className="flex items-center gap-3 py-4">
-          <Eye className="h-5 w-5 text-blue-600 dark:text-blue-400" />
+      <div className="rounded-lg border-2 border-blue-300 bg-blue-50 px-4 py-3">
+        <div className="flex items-center gap-3">
+          <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-blue-100">
+            <Eye className="h-4 w-4 text-blue-600" />
+          </div>
           <div>
-            <p className="font-medium text-blue-900 dark:text-blue-100">
-              Observer Mode
-            </p>
-            <p className="text-sm text-blue-700 dark:text-blue-300">
+            <div className="flex items-center gap-2">
+              <p className="font-semibold text-blue-900">Observer Mode</p>
+              <Badge variant="outline" className="border-blue-300 text-blue-700 text-xs">
+                Read-Only
+              </Badge>
+            </div>
+            <p className="text-sm text-blue-700">
               You have read-only access to view platform statistics and reports.
             </p>
           </div>
-        </CardContent>
-      </Card>
+        </div>
+      </div>
 
       {/* Stats Grid */}
       <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">

src/app/(settings)/settings/profile/page.tsx

@@ -239,19 +239,6 @@ export default function ProfileSettingsPage() {
             />
           </div>
 
-          <div className="flex justify-end">
-            <Button
-              onClick={handleSaveProfile}
-              disabled={updateProfile.isPending}
-            >
-              {updateProfile.isPending ? (
-                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
-              ) : (
-                <Save className="mr-2 h-4 w-4" />
-              )}
-              Save Changes
-            </Button>
-          </div>
         </CardContent>
       </Card>
 
@@ -285,19 +272,6 @@ export default function ProfileSettingsPage() {
             </Select>
           </div>
 
-          <div className="flex justify-end">
-            <Button
-              onClick={handleSaveProfile}
-              disabled={updateProfile.isPending}
-            >
-              {updateProfile.isPending ? (
-                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
-              ) : (
-                <Save className="mr-2 h-4 w-4" />
-              )}
-              Save Preferences
-            </Button>
-          </div>
         </CardContent>
       </Card>
 
@@ -320,22 +294,25 @@ export default function ProfileSettingsPage() {
             maxTags={15}
           />
 
-          <div className="flex justify-end">
-            <Button
-              onClick={handleSaveProfile}
-              disabled={updateProfile.isPending}
-            >
-              {updateProfile.isPending ? (
-                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
-              ) : (
-                <Save className="mr-2 h-4 w-4" />
-              )}
-              Save Expertise
-            </Button>
-          </div>
         </CardContent>
       </Card>
 
+      {/* Save All Profile Changes */}
+      <div className="flex justify-end">
+        <Button
+          onClick={handleSaveProfile}
+          disabled={updateProfile.isPending}
+          size="lg"
+        >
+          {updateProfile.isPending ? (
+            <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+          ) : (
+            <Save className="mr-2 h-4 w-4" />
+          )}
+          Save All Changes
+        </Button>
+      </div>
+
       {/* Change Password */}
       <Card>
         <CardHeader>