feat(brand): add original ATLANTIS logo and brand assets#134

test(brand): cover downloadable and maskable icons

feat(brand): replace Confluence with branching flow trident

test(brand): assert the actual rendered theme

fix(brand): preserve spacing in the compact header

fix(brand): keep header controls visible on narrow screens

style(landing): format branded Astro components

feat(brand): use accessible logo lockups in both apps

feat(brand): add original confluence mark and icon assets