[backfill, May 21] Interactive modal subdivide/inset and GLES2/DRM build path. Refactored modal system into Transform vs Positional families. Positional modals (subdivide, inset) apply topology first, then horizontal drag lerps between position sets — same drag pattern for both. ModalFamily determines cancel behavior (Transform restores positions, Positional triggers undo). Separately: added VMK_PLATFORM_PI cmake flag for Pi Zero 2W — switches raylib to DRM platform, NanoVG to GLES2 backend, selects correct GL headers via vmk_gl.h.