fix: 新增配方去重+编辑者权限+共享去重统一

新增去重:
- 新增配方保存前检查公共库和个人配方同名
- 完全相同提示已有，内容不同显示差异可改名

编辑者权限:
- editor可编辑所有公共配方（前端+后端）
- editor不能编辑精油价目（已有）

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

backend/main.py

@@ -824,9 +824,7 @@ def _check_recipe_permission(conn, recipe_id, user):
     row = conn.execute("SELECT owner_id, name FROM recipes WHERE id = ?", (recipe_id,)).fetchone()
     if not row:
         raise HTTPException(404, "Recipe not found")
-    if user["role"] in ("admin", "senior_editor"):
-        return row
-    if user["role"] in ("editor",) and row["owner_id"] == user.get("id"):
+    if user["role"] in ("admin", "senior_editor", "editor"):
         return row
     raise HTTPException(403, "权限不足")