feat(models): add Chinese verbose_name to all 74 models (Phase 4.0)

为所有 Django 模型添加 Meta.verbose_name 和 verbose_name_plural（中文表名），
覆盖 10 个 app 的全部 74 个业务模型。

Phase 4.0 范围：
- 仅 Meta 类级别中文名（用于 Django Admin、drf-spectacular OpenAPI title、错误信息）
- 字段级 verbose_name= 和 help_text= 留待 Phase 4.1（待 PM 补全 DATA_MODEL 后同步）

变更：
- 20 个 models 文件改动（每个模型 +2 行）
- 8 个 0002/0003 迁移文件（Meta options 变更）
- apps/tenant/migrations/0001_initial.py（之前漏生成的 tenant 模型迁移）

manage.py check: 0 issues。

apps/region/models/region.py

@@ -13,6 +13,8 @@ class District(TimeStampedModel):
 
     class Meta:
         db_table = "districts"
+        verbose_name = "城区"
+        verbose_name_plural = "城区"
         constraints = [
             models.UniqueConstraint(
                 fields=["city", "name"],
@@ -40,6 +42,8 @@ class BusinessArea(TimeStampedModel):
 
     class Meta:
         db_table = "business_areas"
+        verbose_name = "商圈"
+        verbose_name_plural = "商圈"
         constraints = [
             models.UniqueConstraint(
                 fields=["district", "name"],
@@ -68,6 +72,8 @@ class MetroLine(TimeStampedModel):
 
     class Meta:
         db_table = "metro_lines"
+        verbose_name = "地铁线路"
+        verbose_name_plural = "地铁线路"
         ordering = ["city", "sort_order", "name"]
 
     def __str__(self) -> str:
@@ -88,6 +94,8 @@ class MetroStation(TimeStampedModel):
 
     class Meta:
         db_table = "metro_stations"
+        verbose_name = "地铁站点"
+        verbose_name_plural = "地铁站点"
         indexes = [
             models.Index(
                 fields=["metro_line"],
@@ -132,6 +140,8 @@ class School(TimeStampedModel):
 
     class Meta:
         db_table = "schools"
+        verbose_name = "学校"
+        verbose_name_plural = "学校"
         indexes = [
             models.Index(
                 fields=["district"],