Add support subscription panel API with optional free periods.

Co-authored-by: Cursor <cursoragent@cursor.com>

prisma/schema.prisma

@@ -74,6 +74,7 @@ model Tenant {
   /// 0..N hosting/billing servers per sold version (not the same as nodeServer API URL)
   serverAccounts   ServerAccount[]
   pluginSubscriptions PluginSubscription[]
+  supportSubscriptions SupportSubscription[]
 
   @@index([product])
   @@index([isActive])
@@ -279,3 +280,53 @@ model PluginCharge {
   @@index([createdAt])
   @@map("plugin_charges")
 }
+
+/// Support/maintenance subscription for a sold version (0..N per tenant).
+/// Can be free (isFree) for 1|3|6|12 months gift periods.
+model SupportSubscription {
+  id              String    @id @default(cuid())
+  tenantId        String    @map("tenant_id")
+  name            String
+  specs           String?
+  priceRials      Int?      @map("price_rials")
+  /// When true, current period is complimentary (price should be 0)
+  isFree          Boolean   @default(false) @map("is_free")
+  chargedAt       DateTime? @map("charged_at")
+  /// Plan length in months: 1 | 3 | 6 | 12
+  planMonths      Int?      @map("plan_months")
+  expiresAt       DateTime? @map("expires_at")
+  description     String?
+  alertDaysBefore Int       @default(3) @map("alert_days_before")
+  lastAlertDate   DateTime? @map("last_alert_date")
+  isActive        Boolean   @default(true) @map("is_active")
+  createdAt       DateTime  @default(now()) @map("created_at")
+  updatedAt       DateTime  @updatedAt @map("updated_at")
+
+  tenant  Tenant          @relation(fields: [tenantId], references: [id], onDelete: Cascade)
+  charges SupportCharge[]
+
+  @@index([tenantId])
+  @@index([expiresAt])
+  @@index([isActive])
+  @@index([isFree])
+  @@map("support_subscriptions")
+}
+
+model SupportCharge {
+  id             String   @id @default(cuid())
+  supportId      String   @map("support_id")
+  chargedAt      DateTime @map("charged_at")
+  planMonths     Int      @map("plan_months")
+  priceRials     Int      @map("price_rials")
+  isFree         Boolean  @default(false) @map("is_free")
+  expiresAt      DateTime @map("expires_at")
+  note           String?
+  createdById    String?  @map("created_by_id")
+  createdAt      DateTime @default(now()) @map("created_at")
+
+  support SupportSubscription @relation(fields: [supportId], references: [id], onDelete: Cascade)
+
+  @@index([supportId])
+  @@index([createdAt])
+  @@map("support_charges")
+}