feat: add @bchen/ui v0.1.0 — dark-mode token palette and 16px base rule

- dist/tokens.css: canonical light + @media dark semantic-token palette
  extracted from inventory (cross-checked against authd and buchinese).
  Covers --fg, --fg-muted, --bg, --bg-elevated, --surface, --accent*,
  --danger*, --border*, --input-*, --warning, primitive --gray-* scale.
- dist/base.css: `input, textarea, select { font-size: 16px; }` prevents
  iOS Safari auto-zoom on focus.
- tests/tokens.test.ts: vitest — token presence in both light and dark
  blocks; WCAG AA contrast (>=4.5:1 body, >=3.0:1 UI) via inline
  hex-to-luminance math. All 10 tests green.
- tests/base.test.ts: vitest — asserts 16px rule covers all three selectors.
- .gitea/workflows/release.yml: tag-triggered CI — npm ci + npm test,
  CHANGELOG version gate, dist/scripts security grep, Gitea release
  artifact upload.
- README.md: four-step consumer integration guide with copy-pasteable
  snippets (package.json dep, Dockerfile cp, HTML link tags, app CSS).
- CHANGELOG.md: v0.1.0 entry.

npm audit --omit=dev: 0 vulnerabilities

Closes #1

tests/tokens.test.ts

@@ -0,0 +1,133 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'fs';
+
+const css = readFileSync(new URL('../dist/tokens.css', import.meta.url), 'utf-8');
+
+// ---- CSS parser helpers ----
+
+function extractRootBlock(src: string): string {
+  const m = src.match(/:root\s*\{([^}]+)\}/);
+  return m?.[1] ?? '';
+}
+
+function extractDarkBlock(src: string): string {
+  const afterMedia = src.split('@media (prefers-color-scheme: dark)')[1] ?? '';
+  const m = afterMedia.match(/:root\s*\{([^}]+)\}/);
+  return m?.[1] ?? '';
+}
+
+function parseProps(block: string): Map<string, string> {
+  const map = new Map<string, string>();
+  const re = /--([\w-]+)\s*:\s*([^;]+);/g;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(block)) !== null) {
+    map.set(`--${m[1]}`, m[2].trim());
+  }
+  return map;
+}
+
+function resolveToken(value: string, props: Map<string, string>): string {
+  const varRe = /var\(--([\w-]+)\)/;
+  let v = value;
+  for (let i = 0; i < 10 && varRe.test(v); i++) {
+    v = v.replace(varRe, (_, name) => props.get(`--${name}`) ?? 'unresolved');
+  }
+  return v.trim();
+}
+
+// ---- WCAG contrast helpers ----
+
+function expandHex(hex: string): string {
+  const h = hex.replace('#', '');
+  return h.length === 3
+    ? `#${h[0]}${h[0]}${h[1]}${h[1]}${h[2]}${h[2]}`
+    : `#${h}`;
+}
+
+function luminance(hex: string): number {
+  const h = expandHex(hex).replace('#', '');
+  const r = parseInt(h.slice(0, 2), 16) / 255;
+  const g = parseInt(h.slice(2, 4), 16) / 255;
+  const b = parseInt(h.slice(4, 6), 16) / 255;
+  const lin = (c: number) =>
+    c <= 0.04045 ? c / 12.92 : ((c + 0.055) / 1.055) ** 2.4;
+  return 0.2126 * lin(r) + 0.7152 * lin(g) + 0.0722 * lin(b);
+}
+
+function contrast(hex1: string, hex2: string): number {
+  const l1 = luminance(hex1);
+  const l2 = luminance(hex2);
+  const [lighter, darker] = l1 > l2 ? [l1, l2] : [l2, l1];
+  return (lighter + 0.05) / (darker + 0.05);
+}
+
+// ---- Fixtures ----
+
+const rootProps = parseProps(extractRootBlock(css));
+const darkProps = parseProps(extractDarkBlock(css));
+// Merged: dark overrides on top of light primitives so var() refs resolve correctly.
+const mergedDark = new Map([...rootProps, ...darkProps]);
+
+// Tokens that must be explicitly defined in both light and dark blocks.
+const DARK_MODE_TOKENS = [
+  '--bg', '--bg-elevated', '--surface',
+  '--fg', '--fg-muted',
+  '--border-color', '--border-strong',
+  '--accent', '--accent-fg', '--accent-hover',
+  '--danger', '--danger-fg', '--danger-bg',
+  '--input-bg', '--input-fg', '--input-border', '--input-bg-focus',
+];
+
+// ---- Tests ----
+
+describe('tokens.css — token presence', () => {
+  it('defines all dark-mode tokens in :root (light)', () => {
+    for (const token of DARK_MODE_TOKENS) {
+      expect(rootProps.has(token), `${token} missing from :root`).toBe(true);
+    }
+  });
+
+  it('defines all dark-mode tokens in @media (prefers-color-scheme: dark)', () => {
+    for (const token of DARK_MODE_TOKENS) {
+      expect(darkProps.has(token), `${token} missing from @media dark`).toBe(true);
+    }
+  });
+});
+
+describe('tokens.css — WCAG AA contrast (light)', () => {
+  const fg = resolveToken(rootProps.get('--fg')!, rootProps);
+  const fgMuted = resolveToken(rootProps.get('--fg-muted')!, rootProps);
+  const bg = resolveToken(rootProps.get('--bg')!, rootProps);
+  const borderStrong = resolveToken(rootProps.get('--border-strong')!, rootProps);
+
+  it('--fg on --bg >= 4.5:1', () => {
+    expect(contrast(fg, bg)).toBeGreaterThanOrEqual(4.5);
+  });
+
+  it('--fg-muted on --bg >= 4.5:1', () => {
+    expect(contrast(fgMuted, bg)).toBeGreaterThanOrEqual(4.5);
+  });
+
+  it('--border-strong on --bg >= 3.0:1 (UI contrast)', () => {
+    expect(contrast(borderStrong, bg)).toBeGreaterThanOrEqual(3.0);
+  });
+});
+
+describe('tokens.css — WCAG AA contrast (dark)', () => {
+  const fg = resolveToken(mergedDark.get('--fg')!, mergedDark);
+  const fgMuted = resolveToken(mergedDark.get('--fg-muted')!, mergedDark);
+  const bg = resolveToken(mergedDark.get('--bg')!, mergedDark);
+  const borderStrong = resolveToken(mergedDark.get('--border-strong')!, mergedDark);
+
+  it('--fg on --bg >= 4.5:1', () => {
+    expect(contrast(fg, bg)).toBeGreaterThanOrEqual(4.5);
+  });
+
+  it('--fg-muted on --bg >= 4.5:1', () => {
+    expect(contrast(fgMuted, bg)).toBeGreaterThanOrEqual(4.5);
+  });
+
+  it('--border-strong on --bg >= 3.0:1 (UI contrast)', () => {
+    expect(contrast(borderStrong, bg)).toBeGreaterThanOrEqual(3.0);
+  });
+});