Prompt Optimizer v2.9.2

Summary

Fixed desktop updater failures on both stable and prerelease download actions by restoring the missing prerelease preference key and hardening preference-key validation.
Expanded the bilingual image workflow documentation with dedicated multi-image workspace guides, richer text-to-image instructions, and updated navigation.
Added regression coverage so invalid preference keys are rejected cleanly instead of cascading into runtime storage crashes.

Highlights

Desktop users now have a repaired upgrade path in the packaged app: stable and prerelease download flows no longer depend on a missing updater preference constant.

Product Updates

Desktop

Restored the updater preference constant used by the downloadSpecificVersion flow so both stable and prerelease buttons read and write the expected channel setting again.
Added a defensive preference-key guard so malformed updater state is rejected before it can trip low-level storage assertions.

Core/Infra

Added a regression test for invalid preference keys in the preference service to keep the updater failure mode covered.
Refreshed the MkDocs documentation set in both English and Chinese with new multi-image workspace tutorials, stronger text-to-image guidance, and updated onboarding/navigation references.

Fixes

Fixed a desktop updater crash that could surface as [error.storage.read] Failed to get preference: Cannot read properties of undefined (reading 'startsWith') when either download action touched a missing preference key.
Fixed the follow-on failure mode where bad stored updater keys were not rejected early enough inside the shared preference service.

Breaking Changes / Upgrade Notes

No breaking API or data format changes.
If an older desktop build cannot finish the in-app update, install v2.9.2 manually once; subsequent updates will use the repaired updater path.

Developer Notes

This release combines a desktop-side constant restoration with a core-side validation guard and regression test, so both the source bug and leftover bad stored keys fail safely.
The documentation refresh adds dedicated multi-image workspace pages in both locales to match the current image workflow shipped in the app.