chore: add changeset for comprehensive improvements

Author: Dark-Brain07

.changeset/comprehensive-improvements.md

@@ -0,0 +1,11 @@
+---
+"frames.js": patch
+---
+
+### Improvements
+
+- Added comprehensive test coverage for utility functions (`escapeHtmlAttributeValue`, `isValidVersion`, button type guards, `bytesToHexString`, `getByteLength`, `hexStringToUint8Array`, `normalizeCastId`)
+- Added tests for core utilities (`joinPaths`, `parseSearchParams`, `isFrameRedirect`, `isFrameDefinition`)
+- Added tests for error classes (`RequestBodyNotJSONError`, `InvalidFrameActionPayloadError`, `FrameMessageError`)
+- Enhanced JSDoc documentation across utility functions and middleware
+- Improved CONTRIBUTING.md with detailed setup, testing, and PR guidelines