[Feature Request] Add progress bar, pause/resume functionality to support long-duration processing of large codebases

[kterna]

Problem Description

Deepwiki-open currently has the following issues when processing large codebases:

1. Long processing time, with no way for users to track progress.
2. If embedding or LLM calls are interrupted midway(example:llm request time out,rate limited), the entire process needs to be restarted.
3. Lack of pause and resume mechanisms, leading to a poor user experience.

Feature Request

1. Progress Tracking: Add a progress bar and estimated remaining time to the front-end page.
2. Pause/Resume Functionality: Allow users to pause, with the option to persistently save all or part of the progress. Sessions can be resumed later.
3. Error Recovery: Implement a retry mechanism for LLM requests instead of completely skipping them.