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/integration/test_validation_flow.py

@@ -26,7 +26,7 @@ class TestValidationFlow:
         """测试验证包含警告的 YAML"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -49,7 +49,7 @@ slides:
         """测试验证包含错误的 YAML"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -81,7 +81,7 @@ slides:
         """测试收集多个错误"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -110,7 +110,7 @@ slides:
         """测试错误包含位置信息"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -134,7 +134,7 @@ slides:
         """测试验证使用模板的 YAML"""
         yaml_content = f"""
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - template: title-slide
@@ -155,7 +155,7 @@ slides:
         """测试验证缺少必需变量的模板"""
         yaml_content = f"""
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - template: title-slide
@@ -175,7 +175,7 @@ slides:
         # 创建包含错误和警告的 YAML
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -200,7 +200,7 @@ slides:
         """测试验证结果格式化"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -229,7 +229,7 @@ slides:
         """测试验证图片资源"""
         yaml_content = f"""
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements:
@@ -250,7 +250,7 @@ slides:
         """测试验证不存在的图片资源"""
         yaml_content = """
 metadata:
-  size: 16:9
+  size: "16:9"
 
 slides:
   - elements: