LabPneuma: Find your breath

Pneuma is a mobile-first breathing-guide PWA built around a single animated orb that grows and shrinks with each phase. The animation is driven by a pure phaseAt(pattern, elapsed) engine that computes phase, countdown, cycle, and orb scale and skips zero-length holds, so the timing logic is fully unit-testable apart from the UI. A hand-written manifest and a cache-first service worker make it installable and fully offline; it is a from-scratch build you can download and run locally.