feature: Phase3 - Task templates + generation on send

backend/prisma/schema.prisma

@@ -23,6 +23,7 @@ model User {
   sessions           Session[] // 👈 ADD THIS - opposite relation for Session
   sentStaffInvites   StaffInvitation[]
   sentOrganizationInvitations OrganizationInvitation[]
+  assignedLabCaseTasks LabCaseTask[] @relation("LabCaseTaskAssignee")
 
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
@@ -118,6 +119,12 @@ enum TreatmentStatus {
   COMPLETED
 }
 
+enum LabTaskStatus {
+  PENDING
+  IN_PROGRESS
+  COMPLETED
+}
+
 model Treatment {
   id             String          @id @default(uuid())
   organizationId String
@@ -154,6 +161,7 @@ model TreatmentDetail {
   treatment   Treatment                   @relation(fields: [treatmentId], references: [id], onDelete: Cascade)
   attachments TreatmentDetailAttachment[]
   labCaseLink LabCaseDetail?
+  labCaseTasks LabCaseTask[]
 
   @@index([treatmentId, sortOrder])
   @@map("treatment_details")
@@ -190,6 +198,7 @@ model LabCase {
   treatment   Treatment       @relation(fields: [treatmentId], references: [id], onDelete: Cascade)
   details     LabCaseDetail[]
   sends       LabCaseSend[]
+  tasks       LabCaseTask[]
 
   @@index([treatmentId, sortOrder])
   @@map("lab_cases")
@@ -219,6 +228,49 @@ model LabCaseSend {
   @@map("lab_case_sends")
 }
 
+model TreatmentType {
+  id           String  @id @default(uuid())
+  code         String  @unique
+  labDependent Boolean @default(false)
+  sortOrder    Int     @default(0)
+
+  workflowSteps TreatmentWorkflowStep[]
+
+  @@map("treatment_types")
+}
+
+model TreatmentWorkflowStep {
+  id              String @id @default(uuid())
+  treatmentTypeId String
+  stepOrder       Int
+  label           String
+
+  treatmentType TreatmentType @relation(fields: [treatmentTypeId], references: [id], onDelete: Cascade)
+
+  @@unique([treatmentTypeId, stepOrder])
+  @@map("treatment_workflow_steps")
+}
+
+model LabCaseTask {
+  id                String        @id @default(uuid())
+  labCaseId         String
+  treatmentDetailId String
+  tooth             String
+  treatmentType     String
+  stepOrder         Int
+  stepLabel         String
+  assigneeUserId    String?
+  status            LabTaskStatus @default(PENDING)
+
+  labCase  LabCase         @relation(fields: [labCaseId], references: [id], onDelete: Cascade)
+  detail   TreatmentDetail @relation(fields: [treatmentDetailId], references: [id], onDelete: Cascade)
+  assignee User?           @relation("LabCaseTaskAssignee", fields: [assigneeUserId], references: [id], onDelete: SetNull)
+
+  @@unique([labCaseId, tooth, treatmentType, stepOrder])
+  @@index([labCaseId, status])
+  @@map("lab_case_tasks")
+}
+
 model Plan {
   id       String @id @default(uuid())
   name     String @unique // "Solo", "Small", "Medium", "Large", "Enterprise"