feat: 中文化 django-admin 分组与表名 (T-602 层1-3)

- 5 个 app 加 AppConfig.verbose_name(中文分组名)
- 11 个模型加 Meta.verbose_name/verbose_name_plural(中文表名)
- 3 条 AlterModelOptions 迁移(仅 options,无 DB schema 变更)
- LANGUAGE_CODE=zh-hans / USE_I18N=True 已在,Django 自带 admin 与 auth 已中文
- 仅显示层，不改字段名/逻辑/表结构

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/billing/models.py

@@ -52,6 +52,8 @@ class CallRecord(models.Model):
 
     class Meta:
         db_table = "call_record"
+        verbose_name = "调用记录"
+        verbose_name_plural = "调用记录"
         ordering = ("-created_at", "-id")
         constraints = [
             models.CheckConstraint(
@@ -86,6 +88,8 @@ class PricingRule(models.Model):
 
     class Meta:
         db_table = "pricing_rule"
+        verbose_name = "计费规则"
+        verbose_name_plural = "计费规则"
         ordering = ("operation_type", "alias", "resolution")
         constraints = [
             models.UniqueConstraint(
@@ -129,6 +133,8 @@ class ExchangeRate(models.Model):
 
     class Meta:
         db_table = "exchange_rate"
+        verbose_name = "汇率"
+        verbose_name_plural = "汇率"
         ordering = ("-effective_from", "-id")
         constraints = [
             models.CheckConstraint(
@@ -190,6 +196,8 @@ class RechargeOrder(models.Model):
 
     class Meta:
         db_table = "recharge_order"
+        verbose_name = "充值订单"
+        verbose_name_plural = "充值订单"
         ordering = ("-created_at", "-id")
         constraints = [
             models.CheckConstraint(
@@ -256,6 +264,8 @@ class PointsLedger(models.Model):
 
     class Meta:
         db_table = "points_ledger"
+        verbose_name = "点数流水"
+        verbose_name_plural = "点数流水"
         ordering = ("-created_at", "-id")
         constraints = [
             models.CheckConstraint(