fix(admin): issue #147 — Catalog Tree city edit/delete, sort order, subcategory ops

- handleRename: city rename via /api/locations/rename-city (all rows), district via PUT /api/locations/{id}
- City-level delete: DELETE /api/locations/by-city (blocks on dependencies, 400 with counts)
- Sort order: idempotent ensureSortOrderColumns (ALTER TABLE try/catch) + PATCH /api/{type}s/{id}/sort + up/down arrows on district/category/subcategory
- Tree queries order by sort_order asc, then name
- Subcategory rename/delete verified
- tsc clean

admin-next/prisma/schema.prisma

@@ -68,6 +68,7 @@ model Location {
   country   String
   city      String
   district  String   @default("")
+  sortOrder Int      @default(0) @map("sort_order")
   isActive  Int      @default(1) @map("is_active")
   createdAt DateTime @default(now()) @map("created_at")
 
@@ -82,6 +83,7 @@ model Category {
   id         Int       @id @default(autoincrement())
   locationId Int       @map("location_id")
   name       String
+  sortOrder  Int       @default(0) @map("sort_order")
   isActive   Int       @default(1) @map("is_active")
   createdAt  DateTime  @default(now()) @map("created_at")
 
@@ -97,6 +99,7 @@ model Subcategory {
   id          Int      @id @default(autoincrement())
   categoryId  Int      @map("category_id")
   name        String
+  sortOrder   Int      @default(0) @map("sort_order")
   isActive    Int      @default(1) @map("is_active")
   createdAt   DateTime @default(now()) @map("created_at")