fix(contract): 合同签署页面和模板优化

1. 合同模板：身份证号和联系方式显示完整信息，不再使用星号掩码
2. 签署页面：checkbox 默认不选中，用户阅读到底部后才可点击确认

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/services/planting-service/src/domain/aggregates/contract-template.aggregate.ts

@@ -158,15 +158,10 @@ export class ContractTemplate {
     const now = new Date();
     const dateStr = `${now.getFullYear()}年${now.getMonth() + 1}月${now.getDate()}日`;
 
-    // 身份证号脱敏: 只显示前6位和后4位
-    const maskedIdCard = params.userIdCardNumber
-      ? `${params.userIdCardNumber.slice(0, 6)}********${params.userIdCardNumber.slice(-4)}`
-      : '';
-
     let content = this._content;
     content = content.replace(/\{\{USER_PHONE\}\}/g, params.userPhoneNumber || '未认证');
     content = content.replace(/\{\{USER_REAL_NAME\}\}/g, params.userRealName || '未认证');
-    content = content.replace(/\{\{USER_ID_CARD\}\}/g, maskedIdCard || '未认证');
+    content = content.replace(/\{\{USER_ID_CARD\}\}/g, params.userIdCardNumber || '未认证');
     content = content.replace(/\{\{TREE_COUNT\}\}/g, params.treeCount.toString());
     content = content.replace(/\{\{TOTAL_AMOUNT\}\}/g, params.totalAmount.toFixed(2));
     content = content.replace(/\{\{PROVINCE_NAME\}\}/g, params.provinceName);

frontend/mobile-app/lib/features/contract_signing/presentation/pages/contract_signing_page.dart

@@ -836,12 +836,12 @@ class _ContractSigningPageState extends ConsumerState<ContractSigningPage> {
                       width: 24,
                       height: 24,
                       decoration: BoxDecoration(
-                        color: _hasScrolledToBottom ? const Color(0xFFD4AF37) : const Color(0xFFE0E0E0),
+                        color: const Color(0xFFE0E0E0),
                         borderRadius: BorderRadius.circular(4),
+                        border: _hasScrolledToBottom
+                            ? Border.all(color: const Color(0xFFD4AF37), width: 2)
+                            : null,
                       ),
-                      child: _hasScrolledToBottom
-                          ? const Icon(Icons.check, color: Colors.white, size: 16)
-                          : null,
                     ),
                     const SizedBox(width: 12),
                     Expanded(
@@ -853,6 +853,14 @@ class _ContractSigningPageState extends ConsumerState<ContractSigningPage> {
                         ),
                       ),
                     ),
+                    if (!_hasScrolledToBottom)
+                      const Text(
+                        '(请先阅读完合同)',
+                        style: TextStyle(
+                          fontSize: 12,
+                          color: Color(0xFF999999),
+                        ),
+                      ),
                   ],
                 ),
               ),