feat: observer UX overhaul — reports, projects, charts, session & email

- Observer projects: default sort by status (rejected last), sortable status column
- Observer projects: search by country, institution, geographic zone
- Observer project detail: vertical timeline connectors between rounds
- Fix React key warning in ExpandableJurorTable and FilteringReportTabs
- Fix ScoreBadge text always white for better contrast on all backgrounds
- Remove misleading /30 denominator from heatmap juror reviewed count
- INTAKE stats: show Start-ups, Business Concepts, Countries (not States/Categories)
- DiversityMetrics: extractCountry() for country-only display in charts
- Fix nested button hydration error in filtering report mobile view
- Color project titles by outcome in filtering report (green/red/amber)
- Redesign CrossStageComparisonChart: funnel viz + metrics table with attrition %
- Center doughnut chart in StatusBreakdownChart
- Remove redundant RoundTypeStatsCards from evaluation report
- Move evaluation tab bar below overview header, rename to "Juror Assignments"
- Dev email override system (DEV_EMAIL_OVERRIDE env var)
- Session refresh on role change without re-login
- Role switcher in user dropdown menu
- formatCategory() utility for consistent category display
- Activity feed max height constraint

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

src/lib/auth.ts

@@ -283,9 +283,9 @@ export const { handlers, auth, signIn, signOut } = NextAuth({
       }
 
       // On session update, handle impersonation or normal refresh
-      if (trigger === 'update' && session) {
+      if (trigger === 'update') {
         // Start impersonation
-        if (session.impersonate && typeof session.impersonate === 'string') {
+        if (session?.impersonate && typeof session.impersonate === 'string') {
           // Only SUPER_ADMIN can impersonate (defense-in-depth)
           if (token.role === 'SUPER_ADMIN' && !token.impersonating) {
             const targetUser = await prisma.user.findUnique({
@@ -311,7 +311,7 @@ export const { handlers, auth, signIn, signOut } = NextAuth({
           }
         }
         // End impersonation
-        else if (session.endImpersonation && token.impersonating) {
+        else if (session?.endImpersonation && token.impersonating) {
           const original = token.impersonating as { originalId: string; originalRole: UserRole; originalRoles: UserRole[]; originalEmail: string }
           token.id = original.originalId
           token.role = original.originalRole