feat(imitation): add article imitation create flow

Introduce 仿写创作: new list and create views, backend imitation service
and prompt templates, worker task routing for imitation jobs, and one-click
rewrite triggers from question citation sources. Surface source article
URL/title on article list/detail, and restrict failed articles to delete-only.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/admin-web/src/components/ArticleSourceMeta.vue

@@ -3,6 +3,7 @@ import {
   AppstoreOutlined,
   CalendarOutlined,
   ClockCircleOutlined,
+  CopyOutlined,
   EditOutlined,
   TeamOutlined,
   ThunderboltOutlined,
@@ -24,7 +25,7 @@ const sourceLabel = computed(() =>
 const createdAtLabel = computed(() => formatDateTime(props.createdAt));
 
 const sourceVariant = computed<
-  "template" | "custom" | "instant" | "schedule" | "free-create" | "kol" | "default"
+  "template" | "custom" | "instant" | "schedule" | "free-create" | "imitation" | "kol" | "default"
 >(() => {
   if (props.sourceType === "template") {
     return "template";
@@ -32,6 +33,9 @@ const sourceVariant = computed<
   if (props.sourceType === "free_create") {
     return "free-create";
   }
+  if (props.sourceType === "imitation") {
+    return "imitation";
+  }
   if (props.sourceType === "kol") {
     return "kol";
   }
@@ -59,6 +63,8 @@ const badgeIcon = computed<Component>(() => {
       return ThunderboltOutlined;
     case "free-create":
       return EditOutlined;
+    case "imitation":
+      return CopyOutlined;
     case "kol":
       return TeamOutlined;
     default:
@@ -133,6 +139,12 @@ const badgeIcon = computed<Component>(() => {
   color: #18794e;
 }
 
+.article-source-meta__badge--imitation {
+  border: 1px solid #bfdbfe;
+  background: linear-gradient(180deg, #f8fbff 0%, #e6f0ff 100%);
+  color: #1d4ed8;
+}
+
 .article-source-meta__badge--kol {
   border: 1px solid #d6e4ff;
   background: linear-gradient(180deg, #f5f8ff 0%, #eaf1ff 100%);