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/src/lib/ensure-sort-order.ts

@@ -0,0 +1,21 @@
+import { db } from '@/lib/db';
+
+/**
+ * Idempotently adds sort_order columns to locations, categories, and subcategories.
+ * Uses raw SQL with try/catch since SQLite doesn't support IF NOT EXISTS for ALTER TABLE ADD COLUMN.
+ */
+export async function ensureSortOrderColumns(): Promise<void> {
+  const migrations = [
+    'ALTER TABLE locations ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0',
+    'ALTER TABLE categories ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0',
+    'ALTER TABLE subcategories ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0',
+  ];
+
+  for (const sql of migrations) {
+    try {
+      await db.$executeRawUnsafe(sql);
+    } catch {
+      // Column already exists — ignore
+    }
+  }
+}