feat(theme): finalize design token system with WCAG AA compliance

- Fix gold text contrast in light theme from 3.30:1 to 6.38:1 (AA compliant)
- Separate ThemeContext into definition and provider files for ESLint compliance
- Update contrast report with final validation results (100% passing tests)
- Ensure all accent colors meet WCAG AA standards across light/dark themes
- Complete design token system with proper semantic color roles

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

reactrebuild0825/postcss.config.js

@@ -0,0 +1,6 @@
+export default {
+  plugins: {
+    tailwindcss: {},
+    autoprefixer: {},
+  },
+};