feat(app): add WGRplane web UI and backend features

- Add Vue 3 frontend with glassmorphism design (Tailwind CSS)
- Add Go backend handlers: auth, webhooks, stats, scheduler, validation
- Add i18n support (EN, ID, ZH)
- Add Swagger docs and API handlers
- Add nftables integration and plugins support
- Remove deprecated go.mod (migrated to wgrplane)

app/frontend/src/components/glass/GlassButton.vue

@@ -1,8 +1,8 @@
 <template>
-  <button
-    class="px-6 py-2 bg-gradient-to-r from-blue-500 to-purple-600 text-white rounded-lg hover:opacity-90 transition-opacity"
-    v-bind="$attrs"
-  >
+<button
+  class="px-6 py-2 bg-gradient-to-r dark:from-blue-500 dark:to-purple-600 from-blue-600 to-purple-700 text-white rounded-lg hover:opacity-90 transition-opacity"
+  v-bind="$attrs"
+>
     <slot></slot>
   </button>
 </template>

app/frontend/src/components/glass/GlassCard.vue

@@ -1,5 +1,5 @@
 <template>
-  <div class="bg-white/10 backdrop-blur-md border border-white/20 rounded-xl shadow-glass p-6">
+  <div class="dark:bg-white/10 dark:border-white/20 bg-gray-100/80 border-gray-200/50 backdrop-blur-md rounded-xl shadow-glass p-6">
     <slot></slot>
   </div>
 </template>

app/frontend/src/components/glass/GlassInput.vue

@@ -1,6 +1,6 @@
 <template>
-  <input
-    class="w-full bg-white/5 border border-white/20 rounded-lg px-4 py-2 text-white placeholder-white/50 focus:outline-none focus:ring-2 focus:ring-blue-500"
-    v-bind="$attrs"
-  />
+<input
+  class="w-full dark:bg-white/5 dark:border-white/20 bg-gray-100 border-gray-300 rounded-lg px-4 py-2 dark:text-white text-gray-900 dark:placeholder-white/50 placeholder-gray-400 focus:outline-none focus:ring-2 focus:ring-blue-500"
+  v-bind="$attrs"
+/>
 </template>

app/frontend/src/components/glass/GlassToggle.vue

@@ -1,9 +1,9 @@
 <template>
-  <button
-    class="relative w-12 h-6 rounded-full transition-colors"
-    :class="modelValue ? 'bg-blue-500' : 'bg-gray-600'"
-    @click="$emit('update:modelValue', !modelValue)"
-  >
+<button
+  class="relative w-12 h-6 rounded-full transition-colors"
+  :class="modelValue ? 'bg-blue-500' : 'dark:bg-gray-600 bg-gray-300'"
+  @click="$emit('update:modelValue', !modelValue)"
+>
     <span
       class="absolute top-1 left-1 w-4 h-4 bg-white rounded-full transition-transform"
       :class="modelValue ? 'translate-x-6' : ''"