Bump SDK version to 0.4.0 - Add XML filtering feature

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

Author: brandonkachen

sdk/CHANGELOG.md

@@ -2,6 +2,15 @@
 
 All notable changes to the @codebuff/sdk package will be documented in this file.
 
+## [0.4.0] - 2025-01-20
+
+### Added
+
+- XML tool call filtering in stream chunks - filters out `<codebuff_tool_call>` tags while preserving response text
+- Stateful parser handles tags split across chunk boundaries
+- 50-character safety buffer for split tag detection
+- Comprehensive unit tests (17 test cases)
+
 ## [0.3.1]
 
 - `CodebuffClient.run` now does not return `null`. Instead, the `CodebuffClient.run(...).output.type` will be `'error'`.