Create unit tests for pkg/common package

[miabbott]

The pkg/common package (~14 lines) defines constants and version info but has no unit tests.

Test File to Create

• pkg/common/common_test.go

Test Coverage

• Delta operation constants
• Header magic bytes validation
• Version string format

Dependencies

• Depends on Update Go version to 1.25+ #22 (Go 1.25+ update)