feat: add agent task schema and CRUD API (closes #96, closes #97)

apps/api/prisma/schema.prisma

@@ -102,6 +102,19 @@ enum AgentStatus {
   TERMINATED
 }
 
+enum AgentTaskStatus {
+  PENDING
+  RUNNING
+  COMPLETED
+  FAILED
+}
+
+enum AgentTaskPriority {
+  LOW
+  MEDIUM
+  HIGH
+}
+
 enum EntryStatus {
   DRAFT
   PUBLISHED
@@ -145,6 +158,7 @@ model User {
   agentSessions        AgentSession[]
   userLayouts          UserLayout[]
   userPreference       UserPreference?
+  createdAgentTasks    AgentTask[]   @relation("AgentTaskCreator")
 
   @@map("users")
 }
@@ -188,6 +202,7 @@ model Workspace {
   knowledgeEntries KnowledgeEntry[]
   knowledgeTags    KnowledgeTag[]
   cronSchedules    CronSchedule[]
+  agentTasks       AgentTask[]
 
   @@index([ownerId])
   @@map("workspaces")
@@ -573,6 +588,45 @@ model AgentSession {
   @@map("agent_sessions")
 }
 
+model AgentTask {
+  id          String            @id @default(uuid()) @db.Uuid
+  workspaceId String            @map("workspace_id") @db.Uuid
+  
+  // Core fields
+  title       String
+  description String?           @db.Text
+  
+  // Status and priority
+  status      AgentTaskStatus   @default(PENDING)
+  priority    AgentTaskPriority @default(MEDIUM)
+  
+  // Agent configuration
+  agentType   String            @map("agent_type")
+  agentConfig Json              @default("{}") @map("agent_config")
+  
+  // Results
+  result      Json?
+  error       String?           @db.Text
+  
+  // Audit
+  createdById String            @map("created_by_id") @db.Uuid
+  createdAt   DateTime          @default(now()) @map("created_at") @db.Timestamptz
+  updatedAt   DateTime          @updatedAt @map("updated_at") @db.Timestamptz
+  startedAt   DateTime?         @map("started_at") @db.Timestamptz
+  completedAt DateTime?         @map("completed_at") @db.Timestamptz
+  
+  // Relations
+  workspace Workspace @relation(fields: [workspaceId], references: [id], onDelete: Cascade)
+  createdBy User      @relation("AgentTaskCreator", fields: [createdById], references: [id], onDelete: Cascade)
+  
+  @@unique([id, workspaceId])
+  @@index([workspaceId])
+  @@index([workspaceId, status])
+  @@index([workspaceId, priority])
+  @@index([createdById])
+  @@map("agent_tasks")
+}
+
 model WidgetDefinition {
   id String @id @default(uuid()) @db.Uuid