fix(mining-app): QR码解析加固 + debugPrint排查

- 清除不可见字符(BOM/零宽空格)
- 三级宽松解析：正则→Uri.parse→兜底phone=提取
- 添加 [QR_SCAN] 调试日志定位实际扫码值

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mining-app/lib/presentation/pages/asset/send_shares_page.dart

@@ -570,6 +570,7 @@ class _SendSharesPageState extends ConsumerState<SendSharesPage> {
     if (result == null) return;
 
     // 解析二维码内容
+    debugPrint('[QR_SCAN] scanner returned: "$result"');
     final phone = parseTransferQrCode(result);
     if (phone != null) {
       setState(() {

frontend/mining-app/lib/presentation/widgets/qr_scanner_sheet.dart

@@ -250,37 +250,42 @@ class _QrScannerSheetState extends State<QrScannerSheet> {
 /// 返回手机号，解析失败返回 null
 String? parseTransferQrCode(String qrCode) {
   try {
-    final trimmed = qrCode.trim();
+    // 去除首尾空白及不可见字符（BOM、零宽空格等）
+    final trimmed = qrCode.trim().replaceAll(RegExp(r'[\u200B-\u200D\uFEFF\u00A0]'), '');
 
-    // 使用正则表达式匹配，兼容有无 / 的格式
-    // durian://transfer/?phone=xxx 或 durian://transfer?phone=xxx
-    final regex = RegExp(r'^durian://transfer/?[?]phone=(\d{11})$');
+    debugPrint('[QR_SCAN] raw length=${qrCode.length}, trimmed length=${trimmed.length}');
+    debugPrint('[QR_SCAN] raw codeUnits=${qrCode.codeUnits}');
+    debugPrint('[QR_SCAN] trimmed="$trimmed"');
+
+    // 方案1：宽松正则 - 只要包含 durian://transfer 和 phone=11位数字
+    final regex = RegExp(r'durian://transfer[/?].*?phone=(\d{11})');
     final match = regex.firstMatch(trimmed);
-
     if (match != null) {
+      debugPrint('[QR_SCAN] regex matched, phone=${match.group(1)}');
       return match.group(1);
     }
 
-    // 备用方案：使用 Uri.parse
-    final uri = Uri.parse(trimmed);
-
-    // 检查 scheme
-    if (uri.scheme != 'durian') return null;
-
-    // 检查 host (即 authority 部分)
-    if (uri.host != 'transfer') return null;
-
-    // 获取 phone 参数
-    final phone = uri.queryParameters['phone'];
-    if (phone == null || phone.isEmpty) return null;
-
-    // 简单验证手机号格式
-    if (phone.length != 11 || !RegExp(r'^\d{11}$').hasMatch(phone)) {
-      return null;
+    // 方案2：Uri.parse
+    final uri = Uri.tryParse(trimmed);
+    if (uri != null && uri.scheme == 'durian') {
+      final phone = uri.queryParameters['phone'];
+      if (phone != null && RegExp(r'^\d{11}$').hasMatch(phone)) {
+        debugPrint('[QR_SCAN] Uri.parse matched, phone=$phone');
+        return phone;
+      }
     }
 
-    return phone;
+    // 方案3：最宽松兜底 - 字符串中任何 phone=11位数字
+    final fallback = RegExp(r'phone=(\d{11})').firstMatch(trimmed);
+    if (fallback != null) {
+      debugPrint('[QR_SCAN] fallback matched, phone=${fallback.group(1)}');
+      return fallback.group(1);
+    }
+
+    debugPrint('[QR_SCAN] all parsing failed for: "$trimmed"');
+    return null;
   } catch (e) {
+    debugPrint('[QR_SCAN] exception: $e');
     return null;
   }
 }