feat: public read-only share links with permissions — closes #79

Share links:
- Generate a public link in the trip share modal
- Choose what to share: Map & Plan, Bookings, Packing, Budget, Chat
- Permissions enforced server-side
- Delete link to revoke access instantly

Shared trip page (/shared/:token):
- Read-only view with TREK logo, cover image, trip details
- Tabbed navigation with Lucide icons (responsive on mobile)
- Interactive map with auto-fit bounds per day
- Day plan, Bookings, Packing, Budget, Chat views
- Language picker, TREK branding footer

Technical:
- share_tokens DB table with per-field permissions
- Public GET /shared/:token endpoint (no auth)
- Two-column share modal (max-w-5xl)

client/src/i18n/translations/de.ts

@@ -155,6 +155,18 @@ const de: Record<string, string | { name: string; category: string }[]> = {
   'admin.smtp.testSuccess': 'Test-E-Mail erfolgreich gesendet',
   'admin.smtp.testFailed': 'Test-E-Mail fehlgeschlagen',
   'dayplan.icsTooltip': 'Kalender exportieren (ICS)',
+  'share.linkTitle': 'Öffentlicher Link',
+  'share.linkHint': 'Erstelle einen Link den jeder ohne Login nutzen kann, um diese Reise anzuschauen. Nur lesen — keine Bearbeitung möglich.',
+  'share.createLink': 'Link erstellen',
+  'share.deleteLink': 'Link löschen',
+  'share.createError': 'Link konnte nicht erstellt werden',
+  'common.copy': 'Kopieren',
+  'common.copied': 'Kopiert',
+  'share.permMap': 'Karte & Plan',
+  'share.permBookings': 'Buchungen',
+  'share.permPacking': 'Packliste',
+  'share.permBudget': 'Budget',
+  'share.permCollab': 'Chat',
   'settings.on': 'An',
   'settings.off': 'Aus',
   'settings.account': 'Konto',

client/src/i18n/translations/en.ts

@@ -155,6 +155,18 @@ const en: Record<string, string | { name: string; category: string }[]> = {
   'admin.smtp.testSuccess': 'Test email sent successfully',
   'admin.smtp.testFailed': 'Test email failed',
   'dayplan.icsTooltip': 'Export calendar (ICS)',
+  'share.linkTitle': 'Public Link',
+  'share.linkHint': 'Create a link anyone can use to view this trip without logging in. Read-only — no editing possible.',
+  'share.createLink': 'Create link',
+  'share.deleteLink': 'Delete link',
+  'share.createError': 'Could not create link',
+  'common.copy': 'Copy',
+  'common.copied': 'Copied',
+  'share.permMap': 'Map & Plan',
+  'share.permBookings': 'Bookings',
+  'share.permPacking': 'Packing',
+  'share.permBudget': 'Budget',
+  'share.permCollab': 'Chat',
   'settings.on': 'On',
   'settings.off': 'Off',
   'settings.account': 'Account',