feat(payments): add the payments schema, currency domain and money type

Stand up the payments data foundation: a self-contained `payments` Postgres
schema for the in-game currency, wallets, benefits, catalog, orders and the
append-only operations ledger, behind a domain package — nothing wired to real
money yet.

- Migration 00010: the `payments` schema and a NOLOGIN confinement role (ALL on
  payments.*, nothing on backend); the ledger with a BEFORE UPDATE/DELETE
  append-only trigger and a partial idempotency index; the materialised
  balances/benefits; the catalog (atoms seeded) + products + per-method prices;
  the typed single-row config; orders and payment_events. There is no
  cross-schema foreign key — account_id is a plain uuid kept consistent in code,
  which keeps the domain extractable. Expand-contract and reversible.
- Money is a bigint in the currency's minor units carried by a `Money` value
  type (exact, math/big): no float ever touches an amount, and a whole-unit
  currency cannot hold a fraction.
- Extend jetgen to generate the payments schema; construct the service in the
  composition root behind a narrow interface with a boot reachability check.
- Tests: integration (role confinement via SET ROLE, the append-only trigger,
  CHECK constraints, the idempotency index, and a forward+backward migration),
  Money unit tests, and an import-boundary test keeping the payments jet code
  private to the domain.
- Docs: PLAN.md, docs/PAYMENTS.md (+ _ru mirror) updated to the built model.

backend/internal/postgres/jet/payments/table/orders.go

@@ -0,0 +1,111 @@
+//
+// Code generated by go-jet DO NOT EDIT.
+//
+// WARNING: Changes to this file may cause incorrect behavior
+// and will be lost if the code is regenerated
+//
+
+package table
+
+import (
+	"github.com/go-jet/jet/v2/postgres"
+)
+
+var Orders = newOrdersTable("payments", "orders", "")
+
+type ordersTable struct {
+	postgres.Table
+
+	// Columns
+	OrderID           postgres.ColumnString
+	AccountID         postgres.ColumnString
+	Platform          postgres.ColumnString
+	ProductID         postgres.ColumnString
+	ExpectedAmount    postgres.ColumnInteger
+	Currency          postgres.ColumnString
+	Origin            postgres.ColumnString
+	Status            postgres.ColumnString
+	Provider          postgres.ColumnString
+	ProviderPaymentID postgres.ColumnString
+	CreatedAt         postgres.ColumnTimestampz
+	UpdatedAt         postgres.ColumnTimestampz
+
+	AllColumns     postgres.ColumnList
+	MutableColumns postgres.ColumnList
+	DefaultColumns postgres.ColumnList
+}
+
+type OrdersTable struct {
+	ordersTable
+
+	EXCLUDED ordersTable
+}
+
+// AS creates new OrdersTable with assigned alias
+func (a OrdersTable) AS(alias string) *OrdersTable {
+	return newOrdersTable(a.SchemaName(), a.TableName(), alias)
+}
+
+// Schema creates new OrdersTable with assigned schema name
+func (a OrdersTable) FromSchema(schemaName string) *OrdersTable {
+	return newOrdersTable(schemaName, a.TableName(), a.Alias())
+}
+
+// WithPrefix creates new OrdersTable with assigned table prefix
+func (a OrdersTable) WithPrefix(prefix string) *OrdersTable {
+	return newOrdersTable(a.SchemaName(), prefix+a.TableName(), a.TableName())
+}
+
+// WithSuffix creates new OrdersTable with assigned table suffix
+func (a OrdersTable) WithSuffix(suffix string) *OrdersTable {
+	return newOrdersTable(a.SchemaName(), a.TableName()+suffix, a.TableName())
+}
+
+func newOrdersTable(schemaName, tableName, alias string) *OrdersTable {
+	return &OrdersTable{
+		ordersTable: newOrdersTableImpl(schemaName, tableName, alias),
+		EXCLUDED:    newOrdersTableImpl("", "excluded", ""),
+	}
+}
+
+func newOrdersTableImpl(schemaName, tableName, alias string) ordersTable {
+	var (
+		OrderIDColumn           = postgres.StringColumn("order_id")
+		AccountIDColumn         = postgres.StringColumn("account_id")
+		PlatformColumn          = postgres.StringColumn("platform")
+		ProductIDColumn         = postgres.StringColumn("product_id")
+		ExpectedAmountColumn    = postgres.IntegerColumn("expected_amount")
+		CurrencyColumn          = postgres.StringColumn("currency")
+		OriginColumn            = postgres.StringColumn("origin")
+		StatusColumn            = postgres.StringColumn("status")
+		ProviderColumn          = postgres.StringColumn("provider")
+		ProviderPaymentIDColumn = postgres.StringColumn("provider_payment_id")
+		CreatedAtColumn         = postgres.TimestampzColumn("created_at")
+		UpdatedAtColumn         = postgres.TimestampzColumn("updated_at")
+		allColumns              = postgres.ColumnList{OrderIDColumn, AccountIDColumn, PlatformColumn, ProductIDColumn, ExpectedAmountColumn, CurrencyColumn, OriginColumn, StatusColumn, ProviderColumn, ProviderPaymentIDColumn, CreatedAtColumn, UpdatedAtColumn}
+		mutableColumns          = postgres.ColumnList{AccountIDColumn, PlatformColumn, ProductIDColumn, ExpectedAmountColumn, CurrencyColumn, OriginColumn, StatusColumn, ProviderColumn, ProviderPaymentIDColumn, CreatedAtColumn, UpdatedAtColumn}
+		defaultColumns          = postgres.ColumnList{StatusColumn, CreatedAtColumn, UpdatedAtColumn}
+	)
+
+	return ordersTable{
+		Table: postgres.NewTable(schemaName, tableName, alias, allColumns...),
+
+		//Columns
+		OrderID:           OrderIDColumn,
+		AccountID:         AccountIDColumn,
+		Platform:          PlatformColumn,
+		ProductID:         ProductIDColumn,
+		ExpectedAmount:    ExpectedAmountColumn,
+		Currency:          CurrencyColumn,
+		Origin:            OriginColumn,
+		Status:            StatusColumn,
+		Provider:          ProviderColumn,
+		ProviderPaymentID: ProviderPaymentIDColumn,
+		CreatedAt:         CreatedAtColumn,
+		UpdatedAt:         UpdatedAtColumn,
+
+		AllColumns:     allColumns,
+		MutableColumns: mutableColumns,
+		DefaultColumns: defaultColumns,
+	}
+}