feat: [Multi-Modal] Incomplete Processing Pipeline Across Modalities Causes Missing Memory Extraction

[CaralHsi]

Pre-submission checklist | 提交前检查

• I have searched existing issues and this hasn't been mentioned before | 我已搜索现有问题，确认此问题尚未被提及
• I have read the project documentation and confirmed this issue doesn't already exist | 我已阅读项目文档并确认此问题尚未存在
• This issue is specific to MemOS and not a general software issue | 该问题是针对 MemOS 的，而不是一般软件问题

Problem Statement

Issue Description

1. Problem Summary

MultiModalStructMemReader introduces a framework for multimodal inputs, but key parts of the pipeline remain incomplete, causing missing memory extraction across files, images, and mixed-content messages.

2. Expected Improvements
   • Implement fine-mode for all modalities (image, file, tool).
   • Ensure parsers generate valid TextualMemoryItem.
   • SourceMessage reconstruction.
   • Validate through the multimodal test suite.

Willingness to Implement | 实现意愿

• I'm willing to implement this myself | 我愿意自己解决
• I would like someone else to implement this | 我希望其他人来解决