fix(deep-analyzer, srt): correct Zhipu API thinking parameter and fix metadata handling

Root cause:
1. thinking.type="disabled" caused ASR correction accuracy degradation
2. SRTProcessor didn't flatten nested metadata structure
3. Low-quality auto-generated summary section
4. duration field type handling issue

Changes:
- DeepAnalyzer: Remove thinking.type="disabled" to enable default thinking mode
- SRTProcessor: Add metadata flattening for nested structures
- SRTProcessor: Remove low-quality summary section generation
- SRTProcessor: Add duration type checking (string or int)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

kb_workflow/pipeline/processors/srt.py

@@ -166,7 +166,7 @@ class SRTProcessor(BaseProcessor):
             metadata_file: 元数据文件路径
 
         Returns:
-            元数据字典
+            元数据字典（扁平化后的）
         """
         path = Path(metadata_file)
         if not path.exists():
@@ -174,7 +174,21 @@ class SRTProcessor(BaseProcessor):
             return {}
 
         with open(path, 'r', encoding='utf-8') as f:
-            return json.load(f)
+            raw_metadata = json.load(f)
+
+        # 扁平化嵌套结构（与 AnalyzeProcessor._normalize_metadata 一致）
+        if not raw_metadata:
+            return {}
+
+        # 如果已经是扁平结构（顶层有 title）
+        if 'title' in raw_metadata:
+            return raw_metadata
+
+        # 处理嵌套结构 {metadata: {...}, stats: {...}}
+        if 'metadata' in raw_metadata:
+            return raw_metadata['metadata'].copy()
+
+        return raw_metadata
 
     def _extract_tags(self, paragraphs: List[str]) -> List[str]:
         """从段落中提取标签
@@ -216,16 +230,7 @@ class SRTProcessor(BaseProcessor):
         # 构建内容
         content_parts = [frontmatter, ""]
 
-        # 添加摘要（可选）
-        if paragraphs:
-            content_parts.append("## 摘要")
-            content_parts.append("")
-            # 使用第一段作为简单摘要
-            first_para = paragraphs[0][:200] if len(paragraphs[0]) > 200 else paragraphs[0]
-            content_parts.append(first_para + ("..." if len(paragraphs[0]) > 200 else ""))
-            content_parts.append("")
-
-        # 添加内容
+        # 直接添加内容，不生成摘要部分
         content_parts.append("## 内容")
         content_parts.append("")
         for para in paragraphs:
@@ -271,7 +276,12 @@ class SRTProcessor(BaseProcessor):
         # 时长（视频）
         duration = metadata.get('duration', 0)
         if duration:
-            duration_str = self._format_duration(duration)
+            # 如果 duration 已经是字符串格式（如 "05:42"），直接使用
+            # 否则（整数秒数）调用 _format_duration 转换
+            if isinstance(duration, str):
+                duration_str = duration
+            else:
+                duration_str = self._format_duration(duration)
             lines.append(f'duration: {duration_str}')
 
         # BVID