feat(brand): adopt official Kode brand guidelines

- Brand palette: purple #6B35A7 (primary), #000000 (ink), #FFFFFF, #F5F4F0 (canvas)
- Typography: Manrope (UI, 200-800) + Opificio Bold (wordmark/display); drop Inter
- design.md: add wordmarkSecondary token, new display scale (Opificio 72/80)
- foundations: refresh swatches and typography README to match guidelines
- assets/fonts: replace Inter folder with Manrope; add Opificio cuts (Bold/Rounded/Regular)
- fonts.css: register Manrope variable + Opificio cuts; keep Roboto Mono for code only
- examples/web: render the kode wordmark lockup on the off-white canvas
- brand-guidelines: real specs (lockup, palette, typography, logo variant rules)
- README: add brand-at-a-glance, bump version to beta

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tokens/colors.json

@@ -2,15 +2,15 @@
   "$schema": "https://design-tokens.github.io/community-group/format/",
   "color": {
     "brand": {
-      "primary":        { "$value": "#0B5FFF", "$type": "color" },
-      "primary-hover":  { "$value": "#0848C2", "$type": "color" },
-      "primary-pressed":{ "$value": "#063494", "$type": "color" },
-      "secondary":      { "$value": "#FF6B00", "$type": "color" },
-      "accent":         { "$value": "#00C2A8", "$type": "color" }
+      "primary":         { "$value": "#6B35A7", "$type": "color", "$description": "Kode purple — primary brand color." },
+      "primary-hover":   { "$value": "#582A8D", "$type": "color" },
+      "primary-pressed": { "$value": "#45216E", "$type": "color" },
+      "ink":             { "$value": "#000000", "$type": "color", "$description": "Brand black — wordmark and high-emphasis text." },
+      "canvas":          { "$value": "#F5F4F0", "$type": "color", "$description": "Brand off-white — default page surface." }
     },
     "neutral": {
       "0":    { "$value": "#FFFFFF", "$type": "color" },
-      "50":   { "$value": "#F7F8FA", "$type": "color" },
+      "50":   { "$value": "#F5F4F0", "$type": "color", "$description": "Aliased to brand.canvas." },
       "100":  { "$value": "#EDEFF3", "$type": "color" },
       "200":  { "$value": "#D9DCE3", "$type": "color" },
       "300":  { "$value": "#B8BDC9", "$type": "color" },