feat: customer groups for people and companies with tahesab group sync and bulk register

Multiple groups per contact, legacy group text migrated, excel import/export, contacts filter and column, richer create-in-tahesab, match-first bulk export

apps/api/prisma/schema.prisma

@@ -160,6 +160,7 @@ model Organization {
   orgRoles                     OrgRole[]
   teams                        Team[]
   companies                    Company[]
+  customerGroups               CustomerGroup[]
   people                       Person[]
   attendanceEvents             AttendanceEvent[]
   discAssessments              DiscAssessment[]
@@ -477,11 +478,13 @@ model Company {
   city               String?
   postalCode         String?
   address            String?
+  /// قدیمی؛ از نسخهٔ گروه‌بندی، گروه‌ها در CompanyGroupLink هستند
   groupName          String?
   notes              String?
   registeredAt       DateTime?
   tags               String[]      @default([])
   customFields       Json          @default("{}")
+  groupLinks         CompanyGroupLink[]
   people             Person[]
   deals              Deal[]
   activities         Activity[]
@@ -505,6 +508,51 @@ model Company {
   @@index([ownerId])
 }
 
+/// گروه مشتری (مشترک بین اشخاص و شرکت‌ها؛ هر مشتری چند گروه)
+model CustomerGroup {
+  id                  String             @id @default(cuid())
+  organizationId      String
+  organization        Organization       @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  name                String
+  color               String             @default("teal")
+  position            Int                @default(0)
+  /// گروه متناظر در ته‌حساب (GID) روی همان اتصال
+  tahesabConnectionId String?
+  tahesabGid          String?
+  people              PersonGroupLink[]
+  companies           CompanyGroupLink[]
+  createdAt           DateTime           @default(now())
+  updatedAt           DateTime           @updatedAt
+
+  @@unique([organizationId, name])
+  @@index([organizationId, position])
+  @@index([tahesabConnectionId, tahesabGid])
+}
+
+model PersonGroupLink {
+  personId  String
+  person    Person        @relation(fields: [personId], references: [id], onDelete: Cascade)
+  groupId   String
+  group     CustomerGroup @relation(fields: [groupId], references: [id], onDelete: Cascade)
+  /// manual | tahesab — گروهِ ته‌حسابی با همگام‌سازی جایگزین می‌شود؛ دستی دست نمی‌خورد
+  source    String        @default("manual")
+  createdAt DateTime      @default(now())
+
+  @@id([personId, groupId])
+  @@index([groupId])
+}
+
+model CompanyGroupLink {
+  companyId String
+  company   Company       @relation(fields: [companyId], references: [id], onDelete: Cascade)
+  groupId   String
+  group     CustomerGroup @relation(fields: [groupId], references: [id], onDelete: Cascade)
+  createdAt DateTime      @default(now())
+
+  @@id([companyId, groupId])
+  @@index([groupId])
+}
+
 model Person {
   id                      String                   @id @default(cuid())
   organizationId          String
@@ -541,6 +589,7 @@ model Person {
   mood                    PersonMood               @default(newcomer)
   tags                    String[]                 @default([])
   customFields            Json                     @default("{}")
+  groupLinks              PersonGroupLink[]
   loyaltyPoints           Int                      @default(0)
   loyaltyTierId           String?
   loyaltyTier             LoyaltyTier?             @relation(fields: [loyaltyTierId], references: [id], onDelete: SetNull)