chore(mcp): update CHANGELOG for zod v4 upgrade

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: brendan-kellam

packages/mcp/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Bumped `@modelcontextprotocol/sdk` from 1.10.2 to 1.26.0. [#958](https://github.com/sourcebot-dev/sourcebot/pull/958)
+- Upgraded `zod` from `^3.24.3` to `^4.3.6` to fix out-of-memory crashes during TypeScript compilation. [#964](https://github.com/sourcebot-dev/sourcebot/pull/964)
 
 ## [1.0.17] - 2026-02-19