- Core: okForceUtcRuntime, okDate, okCurrentTime, okGetTimezoneOffset, okConvertToGmt, okConvertFromGmt, okGetTimezoneAbbreviation, okIsDstActive, okGetCommonTimezones, okGetManualOffsets
- Bootstrap: forces UTC runtime on startup
- Database: Migration V018 adds published_at_gmt column for dual date storage
- Settings: timezone_string (IANA) + gmt_offset (manual) with priority
- 21 new timezone service tests covering DST, offsets, conversions
- Default timezone: America/Sao_Paulo