Award shortlist UX improvements + configurable invite link expiry

Award shortlist:
- Expandable reasoning text (click to toggle, hover hint)
- Bulk select/deselect all checkbox in header
- Top N projects highlighted with amber background
- New bulkToggleShortlisted backend mutation

Invite link expiry:
- New "Invitation Link Expiry (hours)" field in Security Settings
- Reads from systemSettings `invite_link_expiry_hours` (default 72h / 3 days)
- Email template dynamically shows "X hours" or "X days" based on setting
- All 3 invite paths (bulk create, single invite, bulk resend) use setting

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

src/lib/email.ts

@@ -289,21 +289,29 @@ Together for a healthier ocean.
 /**
  * Generate generic invitation email template (not round-specific)
  */
+function formatExpiryLabel(hours: number): string {
+  if (hours < 24) return `${hours} hour${hours !== 1 ? 's' : ''}`
+  const days = Math.round(hours / 24)
+  return `${days} day${days !== 1 ? 's' : ''}`
+}
+
 function getGenericInvitationTemplate(
   name: string,
   url: string,
-  role: string
+  role: string,
+  expiryHours: number = 72
 ): EmailTemplate {
   const roleLabel = role === 'JURY_MEMBER' ? 'jury member' : role.toLowerCase().replace('_', ' ')
   const article = /^[aeiou]/i.test(roleLabel) ? 'an' : 'a'
   const greeting = name ? `Hello ${name},` : 'Hello,'
+  const expiryLabel = formatExpiryLabel(expiryHours)
 
   const content = `
     ${sectionTitle(greeting)}
     ${paragraph(`You've been invited to join the Monaco Ocean Protection Challenge platform as ${article} <strong>${roleLabel}</strong>.`)}
     ${paragraph('Click the button below to set up your account and get started.')}
     ${ctaButton(url, 'Accept Invitation')}
-    ${infoBox('This link will expire in 7 days.', 'info')}
+    ${infoBox(`This link will expire in ${expiryLabel}.`, 'info')}
   `
 
   return {
@@ -318,7 +326,7 @@ Click the link below to set up your account and get started:
 
 ${url}
 
-This link will expire in 7 days.
+This link will expire in ${expiryLabel}.
 
 ---
 Monaco Ocean Protection Challenge
@@ -1581,9 +1589,10 @@ export async function sendInvitationEmail(
   email: string,
   name: string | null,
   url: string,
-  role: string
+  role: string,
+  expiryHours?: number
 ): Promise<void> {
-  const template = getGenericInvitationTemplate(name || '', url, role)
+  const template = getGenericInvitationTemplate(name || '', url, role, expiryHours)
   const { transporter, from } = await getTransporter()
 
   await transporter.sendMail({