- service.go: Simplify Default() to just call Init() (sync.Once handles idempotency)
- service.go: Add nil check to SetDefault() with panic
- service.go: Add documentation for ModeStrict panic behavior
- loader.go: Add LanguagesErr() to expose directory scan errors
- loader.go: Use path.Join instead of filepath.Join for fs.FS compatibility
- transform.go: Add uint, uint8-64, int8, int16 support to type converters
- grammar.go: Replace deprecated strings.Title with unicode-aware implementation
- i18n_test.go: Add comprehensive concurrency tests with race detector
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>