fix: 配方编号迁移避免重复（一），自动分配下一个可用编号

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/database.py

@@ -298,18 +298,23 @@ def init_db():
             name = name[:m2.start()] + '（' + m2.group(1) + '）'
             c.execute("UPDATE recipes SET name = ? WHERE id = ?", (name, row['id']))
 
-    # Migration: add （一） to base recipes that have numbered siblings
+    # Migration: add number suffix to base recipes that have numbered siblings
     _all_recipes2 = c.execute("SELECT id, name FROM recipes").fetchall()
+    _cn_nums = list('一二三四五六七八九十')
     _base_groups = {}
     for row in _all_recipes2:
         name = row['name']
-        m = _re.match(r'^(.+?)（[一二三四五六七八九十]+）$', name)
+        m = _re.match(r'^(.+?)（([一二三四五六七八九十]+)）$', name)
         if m:
-            _base_groups.setdefault(m.group(1), []).append(row['id'])
+            _base_groups.setdefault(m.group(1), set()).add(m.group(2))
-    # Find bare names that match a numbered group
+    # Find bare names that match a numbered group, assign next available number
     for row in _all_recipes2:
         if row['name'] in _base_groups:
-            c.execute("UPDATE recipes SET name = ? WHERE id = ?", (row['name'] + '（一）', row['id']))
+            used = _base_groups[row['name']]
+            next_num = next((n for n in _cn_nums if n not in used), '十')
+            new_name = row['name'] + '（' + next_num + '）'
+            c.execute("UPDATE recipes SET name = ? WHERE id = ?", (new_name, row['id']))
+            _base_groups[row['name']].add(next_num)
 
     # Seed admin user if no users exist
     count = c.execute("SELECT COUNT(*) FROM users").fetchone()[0]