feat(billing): PaymentProvider + Mock, self-service пополнение баланса

Шаг 0.13 плана production-готовности:
- интерфейс PaymentProvider (createPayment/verifyWebhook/getPaymentStatus)
- MockPaymentProvider с настоящим webhook (sha256-подпись, идемпотентность)
- applySucceededPayment: транзакция с guard, credit, авто-снятие billingBlocked
- роуты payments + confirm-test (только mock) + публичный webhook
- Billing.tsx: Пополнить/Подтвердить (тест), фикс setLocation в рендере
- миграция 0080 billing_payments, 13 новых тестов (78/78)

shared/schema.ts

@@ -87,6 +87,26 @@ export const billingTransactions = pgTable("billing_transactions", {
 export type BillingTransaction = typeof billingTransactions.$inferSelect;
 export type InsertBillingTransaction = typeof billingTransactions.$inferInsert;
 
+// Billing payments (self-service top-ups via payment provider)
+export const billingPayments = pgTable("billing_payments", {
+  id: serial("id").primaryKey(),
+  organizationId: integer("organization_id").notNull().references(() => organizations.id, { onDelete: "cascade" }),
+  provider: varchar("provider", { length: 30 }).notNull(),
+  externalId: varchar("external_id", { length: 255 }).notNull().unique("billing_payments_external_id_key"),
+  amount: numeric("amount", { precision: 10, scale: 2 }).notNull(),
+  currency: varchar("currency", { length: 10 }).notNull().default("RUB"),
+  status: varchar("status", { length: 20 }).notNull().default("pending"), // 'pending' | 'succeeded' | 'canceled'
+  idempotencyKey: varchar("idempotency_key", { length: 255 }).notNull().unique("billing_payments_idempotency_key_key"),
+  metadata: jsonb("metadata"),
+  createdAt: timestamp("created_at").defaultNow(),
+  updatedAt: timestamp("updated_at").defaultNow(),
+}, (table) => ({
+  orgStatusIdx: index("billing_payments_org_status_idx").on(table.organizationId, table.status),
+}));
+
+export type BillingPayment = typeof billingPayments.$inferSelect;
+export type InsertBillingPayment = typeof billingPayments.$inferInsert;
+
 // Users table
 export const users = pgTable("users", {
   id: serial("id").primaryKey(),