docs: add CHANGELOG entry for reasoningSummary

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: brendan-kellam

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Linear issue links in chat responses now render as a rich card-style UI showing the Linear logo, issue identifier, and title instead of plain hyperlinks. [#1060](https://github.com/sourcebot-dev/sourcebot/pull/1060)
 - Added `reasoningEffort` configuration option for the Azure OpenAI provider. [#1101](https://github.com/sourcebot-dev/sourcebot/pull/1101)
+- Added `reasoningSummary` configuration option for the OpenAI and Azure OpenAI providers. [#1102](https://github.com/sourcebot-dev/sourcebot/pull/1102)
 
 ### Changed
 - Links in Ask Sourcebot chat responses now open in a new tab with a subtle external link icon indicator. [#1059](https://github.com/sourcebot-dev/sourcebot/pull/1059)