Release v0.16.0

• Use lightweight same-script copying with configurable marker, Tamil annotation, accent, XML tag, and protected-span handling.
• Disable Vedic accent output and demo accent keys for WX and SLP1.
• Disable Vedic accent output and demo accent keys for Grantha.
• Group scripts as Indic, Roman, and Perso-Arabic, with explicit Vedic accent output support; keep Tamil in Indic with its specialized transliteration handlers.
• Use Roman terminology consistently across engine code, generated data, tooling, demo, and documentation.
• Replace the Malayalam-based tamilExtended profile with Unicode Grantha (grantha) across the engine, Dart/TypeScript/JavaScript APIs, and demo keyboard. The old script ID is removed.