feat(design): Beetroot Riso rebrand — theme, landing, and logos

The brand becomes a risograph-printed contract: flat spot-colors on
beet-tinted cream paper, hard edges, square corners, 2px ink rules,
hard-offset shadows, and a deliberate misregistration layer on every mark.

- theme: light-cream canonical scheme (dark "night edition" via .dark),
  Bricolage Grotesque + Geist + JetBrains Mono, square radii, no glow/
  gradient text. Semantic token API and the one-knob --accent contract
  are unchanged (minor bump, changeset included).
- landing: Manifesto structure — declaration hero, numbered clauses,
  packages as a ruled spec-sheet, ink-bleed AI section, oversized block
  CTA, colophon signature footer. All copy preserved.
- logos: all five marks + favicon redrawn as flat riso prints (no
  gradients), keeping each project's concept.
- design.md: the locked design system for future pages.

Author: btravers

.changeset/beetroot-riso-rebrand.md

@@ -0,0 +1,10 @@
+---
+"@btravstack/theme": minor
+---
+
+Beetroot Riso rebrand — the theme becomes a risograph-printed contract.
+
+- Light cream paper (`oklch(96.5% 0.010 353)`) is now the canonical scheme; dark is the "night edition" soil-black override on `.dark`.
+- Typography: Bricolage Grotesque (display) + Geist (body) + JetBrains Mono (code) replace Montserrat.
+- Square corners everywhere (`--radius-*: 0`), hard-offset shadows (no blur, no glow), 2px ink rules, solid non-frosted navbar, solid ink hero name (no gradient text, no hero glow/float).
+- Non-breaking: all semantic tokens keep their names and the one-knob rebrand contract is unchanged — consumer sites still override only `--accent` (`:root:root { --accent: … }`) and every derived shade follows via `color-mix`.

.hallmark/log.json

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+[
+  {
+    "date": "2026-07-16",
+    "scope": "app",
+    "macrostructure": "Manifesto",
+    "theme": "custom",
+    "theme_axes": "light / display-heavy / chromatic-other (beetroot-pink ~353)",
+    "vibe": "beetroot risograph, contract-as-document, raw, technical",
+    "enrichment": "Tier-B hand-built SVG (flat riso logo set)",
+    "nav": "N7 brutal slab",
+    "footer": "Ft4 dense colophon",
+    "brief": "btravstack org rebrand — landing + @btravstack/theme + logos (Beetroot Riso, design.md locked)"
+  }
+]