feat: 新增项目 GitHub 星标字段与索引

prisma/schema.prisma

@@ -67,6 +67,8 @@ model Project {
   descriptionEn           String?
   content                 String?
   contentEn               String?
+  githubStars             Int                       @default(0)
+  githubStarsUpdatedAt    DateTime?
   status                  ProjectStatus             @default(ACTIVE)
   source                  String?
   createdAt               DateTime                  @default(now())
@@ -80,6 +82,7 @@ model Project {
   @@index([embedding], map: "idx_project_embedding_cosine")
   @@index([slug], map: "idx_project_slug")
   @@index([status, createdAt], map: "idx_project_status_createdAt")
+  @@index([status, githubStars], map: "idx_project_status_github_stars")
   @@map("projects")
 }