feat(content+admin): content ranking + statistics dashboard

- content-svc: template list gains popularity/rating sort modes (use_count_desc,
  popular, rating_desc); new PATCH /v1/templates/{id}/sort to set manual sort
  weight (feature/pin) without a full edit
- admin /admin/ranking: templates ordered by popularity with views/uses/rating
  and inline manual-sort editor
- admin /admin/stats: overview dashboard (users, revenue, paying customers,
  conversion, templates/categories/campaigns/blogs counts) aggregated from
  existing identity + content endpoints
- nav: Dashboard + Ranking links

Completes the epic: SMS/Email/Templates → Marketing → CRM → Ranking + Stats.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

messages/en.json

@@ -326,7 +326,9 @@
       "siteSettings": "Settings",
       "messaging": "Messaging",
       "marketing": "Marketing",
-      "crm": "CRM"
+      "crm": "CRM",
+      "ranking": "Ranking",
+      "stats": "Dashboard"
     },
     "appAdminNodesPage": {
       "title": "Render Nodes",

messages/fa.json

@@ -326,7 +326,9 @@
       "siteSettings": "تنظیمات سایت",
       "messaging": "پیام‌رسانی",
       "marketing": "بازاریابی",
-      "crm": "مدیریت مشتریان"
+      "crm": "مدیریت مشتریان",
+      "ranking": "رتبه‌بندی",
+      "stats": "داشبورد"
     },
     "appAdminNodesPage": {
       "title": "نودهای رندر",