feat: initial blog engine with multi-language, profile, and role system

- Gin + GORM + Tailwind CSS blog engine
- OS-aware config (Linux /etc/blog_go/, Windows ./win/etc/blog_go/)
- SQLite by default, MySQL support via config
- Auto-migrate database + seed admin user on first run
- Session-based auth (login/logout)
- i18n: Chinese/English with auto-detect + manual switch
- Avatar dropdown nav with click-to-toggle menu
- Profile page: avatar upload, edit info, change password
- Role system: admin (full access) and author (profile only)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

templates/admin/dashboard.html

@@ -0,0 +1,42 @@
+{{define "dashboard"}}
+{{template "header" .}}
+<section class="max-w-5xl mx-auto px-4 py-12">
+    <div class="flex items-center justify-between mb-8">
+        <div>
+            <h2 class="text-3xl font-bold text-gray-900">{{index .Tr "dash_title"}}</h2>
+            <p class="text-gray-500 mt-1">{{index .Tr "dash_welcome"}} <span class="font-medium text-gray-700">{{.Username}}</span>!</p>
+        </div>
+        <form action="/logout" method="post" class="m-0">
+            <button
+                type="submit"
+                class="bg-gray-200 text-gray-700 px-4 py-2 rounded-lg font-medium hover:bg-gray-300 transition-colors cursor-pointer"
+            >
+                {{index .Tr "logout"}}
+            </button>
+        </form>
+    </div>
+
+    <!-- Stats -->
+    <div class="grid grid-cols-1 md:grid-cols-3 gap-6 mb-10">
+        <div class="bg-white rounded-xl shadow-sm border border-gray-200 p-6">
+            <p class="text-sm text-gray-500 uppercase tracking-wider">{{index .Tr "dash_posts"}}</p>
+            <p class="text-3xl font-bold text-gray-900 mt-1">0</p>
+        </div>
+        <div class="bg-white rounded-xl shadow-sm border border-gray-200 p-6">
+            <p class="text-sm text-gray-500 uppercase tracking-wider">{{index .Tr "dash_pages"}}</p>
+            <p class="text-3xl font-bold text-gray-900 mt-1">0</p>
+        </div>
+        <div class="bg-white rounded-xl shadow-sm border border-gray-200 p-6">
+            <p class="text-sm text-gray-500 uppercase tracking-wider">{{index .Tr "dash_users"}}</p>
+            <p class="text-3xl font-bold text-gray-900 mt-1">1</p>
+        </div>
+    </div>
+
+    <!-- Placeholder for future features -->
+    <div class="bg-white rounded-xl shadow-sm border border-gray-200 p-8 text-center">
+        <h3 class="text-xl font-semibold text-gray-800 mb-2">{{index .Tr "dash_mgmt_title"}}</h3>
+        <p class="text-gray-500">{{index .Tr "dash_mgmt_desc"}}</p>
+    </div>
+</section>
+{{template "footer" .}}
+{{end}}