Sources move to src/libs/<lib>/{public,private}, one static library
each, layered common, brush, engine, document, canvas, library, ui,
render and app. common holds what is not tied to drawing: undo
history, stroke smoothing, the stroke curve, channel matrices and
update checks. Entry points live in src/apps.
The desktop layout is removed; the application always shows the
studio tablet interface and the separate tablet executable is gone.
App tests drive the studio controls.
Docs move to docs/architecture, docs/roadmap and docs/research with
an index. Headless test commands use the relocated helper script.
24cb4fe1a2