chore: Prepare release v1.0.3

- Move [Unreleased] entries to v1.0.3 section
- Includes comprehensive test additions and testability improvements
- Code coverage improvements and bug fixes

See CHANGELOG.md for details.

Author: rickhohler

CHANGELOG.md

@@ -7,6 +7,26 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- N/A
+
+### Changed
+- N/A
+
+### Deprecated
+- N/A
+
+### Removed
+- N/A
+
+### Fixed
+- N/A
+
+### Security
+- N/A
+
+## [1.0.3] - 2025-12-04
+
 ### Added
 - Added comprehensive unit tests for Builder pattern (12 tests total)
   - Test for BaseBuilder default implementation (notImplemented error)