fix(backurl): stabilize query append and support back-first links

app/Support/BackUrl.php

@@ -74,6 +74,19 @@ class BackUrl
      * 用途：列表页“全部/返回来源”等需要清空筛选但保留 back 的场景。
      */
     public static function withBack(string $path, string $safeBackForLinks = ''): string
+    {
+        return self::appendBack($path, $safeBackForLinks, false);
+    }
+
+    /**
+     * withBack 的变体：将 back 放到 query 的最前面（用于少数对 query 顺序有严格断言的页面/测试）。
+     */
+    public static function withBackFirst(string $path, string $safeBackForLinks = ''): string
+    {
+        return self::appendBack($path, $safeBackForLinks, true);
+    }
+
+    private static function appendBack(string $path, string $safeBackForLinks = '', bool $preferFirst = false): string
     {
         $path = (string) $path;
 
@@ -86,10 +99,26 @@ class BackUrl
             return $path;
         }
 
-        // 若 path 已带 query，则追加 &back=；否则追加 ?back=
-        $sep = str_contains($path, '?') ? '&' : '?';
+        $backQuery = \Illuminate\Support\Arr::query(['back' => $safeBackForLinks]);
 
-        return $path . $sep . \Illuminate\Support\Arr::query(['back' => $safeBackForLinks]);
+        if (!str_contains($path, '?')) {
+            return $path . '?' . $backQuery;
+        }
+
+        [$base, $qs] = explode('?', $path, 2);
+        $qs = trim((string) $qs);
+        $qs = trim($qs, "& ");
+
+        // 处理类似 "/xx?" 或 "/xx?&" 的情况：视为无 query
+        if ($qs === '') {
+            return $base . '?' . $backQuery;
+        }
+
+        if ($preferFirst) {
+            return $base . '?' . $backQuery . '&' . $qs;
+        }
+
+        return $base . '?' . $qs . '&' . $backQuery;
     }
 
     /**
@@ -114,6 +143,25 @@ class BackUrl
         return $url . '#' . $fragment;
     }
 
+    /**
+     * withBackFirst + fragment 的组合：用于少数对 query 顺序有严格断言的页面/测试。
+     */
+    public static function withBackFirstAndFragment(string $path, string $safeBackForLinks = '', string $fragment = ''): string
+    {
+        $url = self::withBackFirst($path, $safeBackForLinks);
+
+        $fragment = ltrim((string) $fragment, '#');
+        if ($fragment === '') {
+            return $url;
+        }
+
+        if (!preg_match('/^[A-Za-z0-9_-]+$/', $fragment)) {
+            return $url;
+        }
+
+        return $url . '#' . $fragment;
+    }
+
     /**
      * 当前路径下的“快捷筛选”链接构造器：
      * - 仅保留指定上下文键（例如 merchant_id/plan_id/keyword/lead_id 等）