Update CHANGELOG.json for v0.11.81 [skip ci]

[github-actions]

Auto-generated: consolidates unreleased entries into v0.11.81 and clears the unreleased array.

[greptile-apps]

Greptile Summary

This PR is an auto-generated changelog update that consolidates unreleased entries into v0.11.81 and clears the unreleased array in desktop/CHANGELOG.json.

• Adds a new "0.11.81" release entry dated 2026-03-07 with a single entry "Bug fixes and improvements"
• Sets "unreleased" to an empty array, matching the automation pattern described in the PR
• No code, logic, or structural issues — change is limited entirely to a JSON data file

Confidence Score: 5/5

• This PR safely updates a JSON changelog file with no functional code changes or structural issues.
• This PR is safe to merge. It only modifies a single JSON data file that consolidates unreleased entries into the v0.11.81 release. There are no code, logic, security, or structural concerns. The change follows the established changelog schema and automation pattern used in prior releases.
• No files require special attention.

_{Last reviewed commit: 5b8551f}