feat: add prompt service (#6241)

fix CLOUD-19

packages/backend/server/schema.prisma

@@ -30,6 +30,7 @@ model User {
   pagePermissions      WorkspacePageUserPermission[]
   connectedAccounts    ConnectedAccount[]
   sessions             UserSession[]
+  AiSession            AiSession[]
 
   @@map("users")
 }
@@ -96,6 +97,7 @@ model Workspace {
   permissions     WorkspaceUserPermission[]
   pagePermissions WorkspacePageUserPermission[]
   features        WorkspaceFeatures[]
+  AiSession       AiSession[]
 
   @@map("workspaces")
 }
@@ -321,6 +323,8 @@ model Snapshot {
   // but the created time of last seen update that has been merged into snapshot.
   updatedAt   DateTime @map("updated_at") @db.Timestamptz(6)
 
+  AiSession AiSession[]
+
   @@id([id, workspaceId])
   @@map("snapshots")
 }
@@ -422,6 +426,47 @@ model UserInvoice {
   @@map("user_invoices")
 }
 
+enum AiPromptRole {
+  system
+  assistant
+  user
+}
+
+model AiPrompt {
+  id        String       @id @default(uuid()) @db.VarChar
+  // prompt name
+  name      String       @db.VarChar(20)
+  // if a group of prompts contains multiple sentences, idx specifies the order of each sentence
+  idx       Int          @db.Integer
+  // system/assistant/user
+  role      AiPromptRole
+  // prompt content
+  content   String       @db.Text
+  createdAt DateTime     @default(now()) @map("created_at") @db.Timestamptz(6)
+
+  @@unique([name, idx])
+  @@map("ai_prompts")
+}
+
+model AiSession {
+  id          String   @id @default(uuid()) @db.VarChar
+  userId      String   @map("user_id") @db.VarChar
+  workspaceId String   @map("workspace_id") @db.VarChar
+  docId       String   @map("doc_id") @db.VarChar
+  promptName  String   @map("prompt_name") @db.VarChar
+  action      Boolean  @db.Boolean
+  model       String   @db.VarChar
+  messages    Json     @db.Json
+  createdAt   DateTime @default(now()) @map("created_at") @db.Timestamptz(6)
+  updatedAt   DateTime @updatedAt @map("updated_at") @db.Timestamptz(6)
+
+  user      User      @relation(fields: [userId], references: [id], onDelete: Cascade)
+  workspace Workspace @relation(fields: [workspaceId], references: [id], onDelete: Cascade)
+  doc       Snapshot  @relation(fields: [docId, workspaceId], references: [id, workspaceId], onDelete: Cascade)
+
+  @@map("ai_sessions")
+}
+
 model DataMigration {
   id         String    @id @default(uuid()) @db.VarChar(36)
   name       String    @db.VarChar