#118 Use the gf1 gl0w logo in the header/footer lockup

Problem

The #70 lockup still renders the gl0w brand as a monospace text placeholder (gl0w in a bordered box). The real gl0w mark is now available at ~/src/code/gf1/website/assets/logo.svg (inverted-triangle G, currentColor).

Fix

• Vendor the exact SVG as static/gl0w.svg and emit it in dist/gl0w.svg.
• Inline the mark in the header lockup and footer brand so currentColor follows the dark/light theme and hover states.
• Keep the hu13 diamond-hub logo and the hu13 — a gl0w project tagline.
• Add a regression test for the gf1 viewBox/path geometry, the absence of the text placeholder, and the emitted asset.