重构 API 为 8 领域 + 应用层架构

将后端模块拆分为 domains、applications、shared 三层，结算计算器移入 domain 纯函数目录，API 路径与测试保持不变。

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

apps/api/src/domains/operations/i18n/i18n.module.ts

@@ -0,0 +1,8 @@
+import { Module } from '@nestjs/common';
+import { I18nService } from './i18n.service';
+
+@Module({
+  providers: [I18nService],
+  exports: [I18nService],
+})
+export class I18nModule {}

apps/api/src/domains/operations/i18n/i18n.service.ts

@@ -0,0 +1,55 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../../../shared/prisma/prisma.service';
+import { DEFAULT_LOCALE } from '@thebet365/shared';
+
+const FALLBACK_ORDER = ['en-US', 'zh-CN', 'ms-MY'];
+
+@Injectable()
+export class I18nService {
+  constructor(private prisma: PrismaService) {}
+
+  async getMessages(locale: string) {
+    const messages = await this.prisma.i18nMessage.findMany({
+      where: { locale: { in: [locale, ...FALLBACK_ORDER] } },
+    });
+
+    const byKey: Record<string, Record<string, string>> = {};
+    for (const m of messages) {
+      if (!byKey[m.msgKey]) byKey[m.msgKey] = {};
+      byKey[m.msgKey][m.locale] = m.value;
+    }
+
+    const result: Record<string, string> = {};
+    for (const [key, locales] of Object.entries(byKey)) {
+      result[key] =
+        locales[locale] ||
+        FALLBACK_ORDER.map((l) => locales[l]).find(Boolean) ||
+        key;
+    }
+    return result;
+  }
+
+  async upsertMessage(msgKey: string, locale: string, value: string) {
+    return this.prisma.i18nMessage.upsert({
+      where: { msgKey_locale: { msgKey, locale } },
+      create: { msgKey, locale, value },
+      update: { value },
+    });
+  }
+
+  async listMissing() {
+    const keys = await this.prisma.i18nMessage.groupBy({ by: ['msgKey'] });
+    const locales = ['zh-CN', 'ms-MY', 'en-US'];
+    const missing = [];
+
+    for (const { msgKey } of keys) {
+      for (const locale of locales) {
+        const exists = await this.prisma.i18nMessage.findUnique({
+          where: { msgKey_locale: { msgKey, locale } },
+        });
+        if (!exists) missing.push({ msgKey, locale });
+      }
+    }
+    return missing;
+  }
+}