fix: use quoted strings for size values in YAML to prevent time parsing

YAML parser interprets 16:9 as time format (16h 9m = 969s).
Using quoted strings "16:9" ensures correct string parsing.

tests/e2e/test_check_cmd.py

@@ -37,7 +37,7 @@ class TestCheckCmd:
         # 创建包含错误的 YAML
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -59,7 +59,7 @@ slides:
         """测试只有警告的 YAML（验证通过但有警告）"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -81,7 +81,7 @@ slides:
         """测试检查使用模板的 YAML"""
         yaml_content = f"""
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - template: title-slide
@@ -99,7 +99,7 @@ slides:
         """测试检查使用不存在模板的 YAML"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - template: nonexistent
@@ -118,7 +118,7 @@ slides:
         """测试检查报告多个错误"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -147,7 +147,7 @@ slides:
         """测试检查包含位置信息"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -170,7 +170,7 @@ slides:
         """测试检查缺少必需变量的模板"""
         yaml_content = f"""
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - template: title-slide