Add a small internal warehouse and party balances when Tahesab is off.

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

apps/api/prisma/schema.prisma

@@ -180,6 +180,9 @@ model Organization {
   noteAiSuggestions     NoteAiSuggestion[]
   accountingConnections AccountingConnection[]
   accountingSyncJobs    AccountingSyncJob[]
+  warehouses            Warehouse[]
+  stockMovements        StockMovement[]
+  partyOpenings         PartyOpeningBalance[]
 }
 
 model User {
@@ -283,6 +286,7 @@ model Person {
   memoryItems           MemoryItem[]
   accountingLinks       PersonAccountingLink[]
   accountingDocuments   AccountingDocumentLog[]
+  openingBalances       PartyOpeningBalance[]
   createdAt             DateTime                 @default(now())
   updatedAt             DateTime                 @updatedAt
 
@@ -545,6 +549,7 @@ model Product {
   lineItems         DealLineItem[]
   quoteLineItems    QuoteLineItem[]
   invoiceLineItems  InvoiceLineItem[]
+  stockMovements    StockMovement[]
   createdAt         DateTime       @default(now())
   updatedAt         DateTime       @updatedAt
 
@@ -725,6 +730,7 @@ model Invoice {
   lineItems      InvoiceLineItem[]
   payments       Payment[]
   installments   InvoiceInstallment[]
+  stockMovements StockMovement[]
   createdAt      DateTime             @default(now())
   updatedAt      DateTime             @updatedAt
 
@@ -1210,3 +1216,57 @@ model AccountingSyncJob {
 
   @@index([organizationId, createdAt])
 }
+
+/// انبار داخلی — وقتی ته‌حساب وصل نیست
+model Warehouse {
+  id             String          @id @default(cuid())
+  organizationId String
+  organization   Organization    @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  name           String
+  isDefault      Boolean         @default(true)
+  movements      StockMovement[]
+  createdAt      DateTime        @default(now())
+  updatedAt      DateTime        @updatedAt
+
+  @@index([organizationId, isDefault])
+}
+
+/// گردش کالا؛ مقدار مثبت ورود، منفی خروج
+model StockMovement {
+  id             String       @id @default(cuid())
+  organizationId String
+  organization   Organization @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  warehouseId    String
+  warehouse      Warehouse    @relation(fields: [warehouseId], references: [id], onDelete: Cascade)
+  productId      String
+  product        Product      @relation(fields: [productId], references: [id], onDelete: Cascade)
+  /// opening | purchase | sale | credit | adjustment
+  type           String
+  quantity       Decimal      @db.Decimal(18, 2)
+  note           String?
+  invoiceId      String?
+  invoice        Invoice?     @relation(fields: [invoiceId], references: [id], onDelete: Cascade)
+  occurredAt     DateTime     @default(now())
+  createdAt      DateTime     @default(now())
+
+  @@index([organizationId, productId, occurredAt])
+  @@index([invoiceId])
+  @@index([warehouseId])
+}
+
+/// مانده اول دوره طرف‌حساب (مثبت = بدهکار ما)
+model PartyOpeningBalance {
+  id             String       @id @default(cuid())
+  organizationId String
+  organization   Organization @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  personId       String
+  person         Person       @relation(fields: [personId], references: [id], onDelete: Cascade)
+  amount         Decimal      @db.Decimal(18, 2)
+  currency       String       @default("IRR")
+  note           String?
+  createdAt      DateTime     @default(now())
+  updatedAt      DateTime     @updatedAt
+
+  @@unique([organizationId, personId])
+  @@index([personId])
+}