branding: centralize brand name/logo; update metadata, headers, nav, ask-ai UI, uploader, space placeholder, and injected badge to use BRAND_NAME/BRAND_ICON_SRC

chore(embed): hide login/save/gallery/help globally on Space via NEXT_PUBLIC_EMBED_MODE=true; UI gating for banner and nav; minor cleanup

chore: enable forceConsistentCasingInFileNames; fix <ul> children to be valid <li> only

wip target element + no follow up option

initial commit