fix: restore discovery task pipeline

prisma/schema.prisma

@@ -25,6 +25,29 @@ model ExternalLink {
   @@map("external_links")
 }
 
+model ProjectDiscoveryTask {
+  id                 String     @id @default(cuid())
+  status             TaskStatus @default(PENDING)
+  sourceUrl          String
+  sourceType         String     @default("manual")
+  explorationData    Json?
+  explorationSummary String?
+  errorMessage       String?
+  retryCount         Int        @default(0)
+  lastRetryAt        DateTime?
+  projectId          String?
+  createdAt          DateTime   @default(now())
+  startedAt          DateTime?
+  completedAt        DateTime?
+  updatedAt          DateTime   @updatedAt
+  project            Project?   @relation(fields: [projectId], references: [id])
+
+  @@index([projectId], map: "idx_task_project_id")
+  @@index([sourceUrl], map: "idx_task_source_url")
+  @@index([status, createdAt], map: "idx_task_status_created")
+  @@map("project_discovery_tasks")
+}
+
 model ProjectTag {
   projectId String
   tagId     String
@@ -37,24 +60,25 @@ model ProjectTag {
 }
 
 model Project {
-  id                   String                 @id @default(cuid())
-  name                 String
-  nameEn               String?
-  slug                 String                 @unique
-  description          String
-  descriptionEn        String?
-  content              String?
-  contentEn            String?
-  githubStars          Int                    @default(0)
-  githubStarsUpdatedAt DateTime?
-  status               ProjectStatus          @default(ACTIVE)
-  source               String?
-  createdAt            DateTime               @default(now())
-  updatedAt            DateTime               @updatedAt
-  embedding            Unsupported("vector")?
-  embeddingUpdatedAt   DateTime?
-  links                ExternalLink[]
-  tags                 ProjectTag[]
+  id                    String                 @id @default(cuid())
+  name                  String
+  nameEn                String?
+  slug                  String                 @unique
+  description           String
+  descriptionEn         String?
+  content               String?
+  contentEn             String?
+  githubStars           Int                    @default(0)
+  githubStarsUpdatedAt  DateTime?
+  status                ProjectStatus          @default(ACTIVE)
+  source                String?
+  createdAt             DateTime               @default(now())
+  updatedAt             DateTime               @updatedAt
+  embedding             Unsupported("vector")?
+  embeddingUpdatedAt    DateTime?
+  links                 ExternalLink[]
+  projectDiscoveryTasks ProjectDiscoveryTask[]
+  tags                  ProjectTag[]
 
   @@index([embedding], map: "idx_project_embedding_cosine")
   @@index([slug], map: "idx_project_slug")
@@ -118,6 +142,13 @@ enum ProjectStatus {
   ARCHIVED
 }
 
+enum TaskStatus {
+  PENDING
+  IN_PROGRESS
+  COMPLETED
+  FAILED
+}
+
 enum TagCategory {
   FIXED_PROJECT_TYPE
   TECH_STACK