feat: group activities into boards with their own stages, like sales pipelines

Existing stages and activities move into a default board per environment; new activities pick a board in the form.

apps/api/prisma/schema.prisma

@@ -224,6 +224,7 @@ model Organization {
   reservationAppointments      ReservationAppointment[]
   leads                        Lead[]
   leadStages                   LeadStage[]
+  activityBoards               ActivityBoard[]
   activityStages               ActivityStage[]
   activityTypeDefs             ActivityTypeDef[]
   leadEvents                   LeadEvent[]
@@ -686,10 +687,29 @@ model Deal {
 }
 
 /// مراحل/ستون‌های فعالیت (تب و کانبان) — kind وضعیت فعالیت داخل این مرحله را تعیین می‌کند
+/// گروه فعالیت (مثل مسیر فروش برای معاملات): هر گروه ستون‌های خودش را دارد
+model ActivityBoard {
+  id             String          @id @default(cuid())
+  organizationId String
+  organization   Organization    @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  name           String
+  isDefault      Boolean         @default(false)
+  position       Int             @default(0)
+  stages         ActivityStage[]
+  activities     Activity[]
+  createdAt      DateTime        @default(now())
+  updatedAt      DateTime        @updatedAt
+
+  @@unique([organizationId, name])
+  @@index([organizationId, position])
+}
+
 model ActivityStage {
   id             String         @id @default(cuid())
   organizationId String
   organization   Organization   @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  boardId        String
+  board          ActivityBoard  @relation(fields: [boardId], references: [id], onDelete: Cascade)
   name           String
   position       Int            @default(0)
   color          String         @default("green")
@@ -698,8 +718,9 @@ model ActivityStage {
   createdAt      DateTime       @default(now())
   updatedAt      DateTime       @updatedAt
 
-  @@unique([organizationId, name])
+  @@unique([boardId, name])
   @@index([organizationId, position])
+  @@index([boardId, position])
 }
 
 /// نوع فعالیت قابل تعریف توسط سازمان با فیلدهای اختصاصی
@@ -764,6 +785,9 @@ model Activity {
   createdBy         User?            @relation("ActivityCreator", fields: [createdById], references: [id], onDelete: SetNull)
   notes             Note[]
   routineTasks      RoutineTask[]
+  /// گروه فعالیت؛ null = گروه پیش‌فرض محیط
+  boardId           String?
+  board             ActivityBoard?   @relation(fields: [boardId], references: [id], onDelete: SetNull)
   /// مرحله (ستون کانبان)؛ null یا مرحلهٔ ناهم‌نوع با status → اولین مرحلهٔ هم‌نوع
   stageId           String?
   stage             ActivityStage?   @relation(fields: [stageId], references: [id], onDelete: SetNull)
@@ -781,6 +805,7 @@ model Activity {
   updatedAt         DateTime         @updatedAt
 
   @@index([stageId])
+  @@index([boardId])
   @@index([typeDefId])
   @@index([leadId])
   @@index([organizationId, status, dueAt])