#70 Brand v1: gl0w + hu13 lockup, branded footer with gl0w.world, og:image, theme-aware logo

Today the site has no gl0w branding anywhere — zero references to gl0w.world in any generated page. The only attribution is the muted right-aligned footer line generated from a snapshot of a repo and its f0rge · master @ 6f379f8.

Owner will vendor the gl0w logo asset; this issue wires it in and owns the lockup, footer, and metadata.

Current problems

1. Header logo is static/logo.svg (96×32, 3:1) inside .brand-lockup > img.site-logo with width:3rem;height:3rem. The later rule img,svg{max-width:100%;height:auto} wins, so it renders 48×16 — an illegible chip in a 56px nav.
2. logo.svg hardcodes <rect fill="#1a1b26"> and a #292e42 border, so light mode shows a dark slab (light theme page bg is #d5d6db).
3. Footer: one muted line, right-aligned, no links, contrast 2.76:1 (dark) / 4.26:1 (light).
4. No og:image (og:title/og:type exist) → link previews carry no brand.

Scope

• Header lockup: gl0w mark + hu13 wordmark (e.g. gl0w glyph then hu13), sized to the nav (mark ≥ 24px, lockup ≤ 32px tall), linked to /. Keep the hu13 mark as the product identity; gl0w is the maker. Vendor the gl0w SVG under static/ (owner supplies); if it needs a dark/light variant, emit both and swap with @media (prefers-color-scheme) or make it currentColor.
• Theme-aware logo: remove the hardcoded background rect from logo.svg (or use fill="none" + currentColor strokes) so it works on both themes; regenerate favicon.svg if it shares the same rect.
• Footer: left-aligned brand block — gl0w mark + hu13 by gl0w + source at gl0w.world (external link, rel="noopener") — then the existing snapshot line (generated from a snapshot … · branch @ sha) demoted to small --fg-dim. One footer.site-footer per page, page_site/page_site_with_provenance both use it.
• og:image: a static 1200×630 lockup (static/og.png or SVG), theme-neutral (dark bg is fine for previews), with og:image:width/height and twitter:card=summary_large_image.
• agents.md / README should mention gl0w as the source (one line, not marketing).

Acceptance

• header shows gl0w + hu13 legibly at 1280 and 390, in both themes
• logo/favicon contain no hardcoded page background
• every page's footer links to gl0w.world and still carries branch@sha
• og:image present and resolves to a real file in dist/
• footer text passes AA contrast (see the light-theme issue)