[autofix] jimeng/generate: TIMEOUT

## Summary
OpenCLI autofix repaired this adapter locally, and the retry passed.

## Adapter
- Site: `jimeng`
- Command: `generate`
- OpenCLI version: `latest`

## Original failure
- Error code: `TIMEOUT`

~~~
Generation may still be in progress (selector length mismatch due to virtualized list)
~~~

## Local fix summary

~~~
1. Replaced `document.execCommand` with `textContent` + `InputEvent` for reliable text insertion.
2. Changed the success detection logic from counting total images (which fails on virtualized lists) to monitoring the `src` of the first image in the feed, with a state machine waiting for the '生成中' indicator to start and finish.
~~~

_Issue filed by OpenCLI autofix after a verified local repair._

Start at the jimeng/generate adapter entry point and reproduce the TIMEOUT involving the virtualized image list. Verify the text insertion and generation-state detection against the reported failure; done means the retry completes without the selector-length timeout and correctly observes generation starting and finishing.

Written by the indexing model from the issue text.