Document the planned native Android client (bookhoard-app): product
vision, tech stack and rationale (Kotlin + Compose + Readium over
hybrid/Flutter/KMP alternatives), module architecture, offline-first
sync flow over the existing REST/WebSocket API, reader and comics/manga
UX, iOS posture, distribution and licensing, and a five-milestone
roadmap. The client is a thin, offline-first consumer of the server's
existing device registration, universal progress, annotation, and
conflict-resolution APIs — no server changes required.
