SJ Paint v0.2.20

Outline and Fill now use selectable menus with independent style previews. Changing styles keeps pending shapes and curves editable; keyboard navigation, cancellation and Undo/Redo retain their existing owners. Shape controls remain available in narrow windows, and menus fit short viewports.

Verification: 963 browser checks on each platform, 422 hidden Windows checks, 417 isolated Linux checks and 47 Linux installer checks passed in CI 38882342638. Windows and Linux app payloads match exactly. Native chooser responses are simulated. Actual AI inference was skipped; remaining AI work is deferred. Full Microsoft Paint parity remains unfinished.