Give the GK monogram a light mode version

In light mode the header, footer and post placeholders show the monogram
on a pale disc with deep gold rings and ink letters, with a soft edge so
it sits apart from the Starlight page. The light file is written by the
light motifs script.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aSbo2D1qP8cMFQCykf7kx

packages/ui/scripts/light-motifs.mjs

@@ -1,7 +1,8 @@
 /**
  * Writes the light and foil versions of the motif SVGs from the dark originals
  * in src/assets/motifs, using the inks Greg picked on the light motif board
- * (2026-10-18). Run after a motif changes: node packages/ui/scripts/light-motifs.mjs
+ * (2026-10-18), and the light GK monogram in src/assets/brand/light. Run after
+ * a motif or the monogram changes: node packages/ui/scripts/light-motifs.mjs
  *
  *   light/       deep gold line: the dark inks swapped for Starlight-page inks, glow removed
  *   foil/        the dark seal with its gold as foil, glow kept
@@ -63,3 +64,15 @@ for (const f of files) {
   }
 }
 console.log(`${files.length} motifs written`);
+
+// The GK monogram on Starlight: a pale disc, deep gold rings and ink letters.
+const MONOGRAM = {
+  ...LIGHT,
+  "#131C2B": "#FFFFFF",
+  "#1F3B49": "#ECE6D8",
+  "#15232F": "#FBF9F4",
+};
+const brand = join(dir, "../brand");
+mkdirSync(join(brand, "light"), { recursive: true });
+writeFileSync(join(brand, "light", "gk-monogram.svg"), recolor(readFileSync(join(brand, "gk-monogram.svg"), "utf8"), MONOGRAM));
+console.log("monogram written");