feat: landing analytics goals, daily bar chart, referrer tracking, contact persistence

- Add per-landing analytics goals (view/click) with admin editor toggle
- Add sticky pay button option for mobile landing pages
- Add daily purchases bar chart (created vs paid) to landing stats
- Replace single purchase count with created/paid split in stats summary
- Add referrer tracking to purchases with hostname display in stats
- Add time display to purchase cards alongside date
- Pass user timezone to stats API for correct daily grouping
- Clamp referrer (500 chars) and subid (255 chars) to backend limits
- Persist contact value per-landing-slug in localStorage
- Fire buy_success analytics goal on successful delivery
- Export USER_TIMEZONE from format utils
- Add analytics/stats translations for fa.json and zh.json locales

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/pages/AdminLandings.tsx

@@ -180,7 +180,19 @@ function SortableLandingCard({
               </div>
               <div className="text-sm text-dark-400">
                 <span>
-                  {landing.purchase_stats.total} {t('admin.landings.purchaseCount')}
+                  {landing.purchase_stats.total}
+                  <span className="ml-1 text-dark-600">
+                    {t('admin.landings.stats.created', 'created')}
+                  </span>
+                  <span className="mx-1 text-dark-600">/</span>
+                  <span className="text-success-400">
+                    {landing.purchase_stats.paid +
+                      landing.purchase_stats.delivered +
+                      landing.purchase_stats.pending_activation}
+                  </span>
+                  <span className="ml-1 text-dark-600">
+                    {t('admin.landings.stats.paid', 'paid')}
+                  </span>
                 </span>
               </div>
             </div>