Add the design system extracted from the app

design/ holds the tokens for all six themes, the type scale, spacing,
radii and sizes, the brand and usage guidelines, a guide and static
preview for each component, the logo and icons as SVG, and wireframes of
the tablet and foldable column layout.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RhmDdrN5hgWrgRcFLAMsV6

design/components/SectionLabel/README.md

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+# SectionLabel
+
+The heading over each group in the reading settings sheet.
+
+- **Consumer provides:** the text.
+- `title-small` in `primary`, with `space-12` above it. Not a link and not tappable; it only names the group of chips, slider or toggle beneath.

design/components/SectionLabel/preview.html

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+<!-- @dsCard group="Selection" height=90 -->
+<!doctype html><html><head><meta charset="utf-8"><style>body{margin:0;background:var(--surface)} .pad{padding:16px} .stack{display:flex;flex-direction:column;gap:16px} .cap{font:12px/16px var(--font-libron);color:var(--on-surface-variant);direction:ltr;text-align:left;margin-bottom:4px}</style></head><body>
+<div class="gj pad" dir="rtl" lang="fa"><div class="gj-label">پوسته</div><div class="gj-label">اندازهٔ متن</div></div>
+</body></html>