[rrealmrezarajabi]

Closes #87

Summary

• isolate theme context consumption to small theme controls
• move theme-dependent page colors to CSS variables
• prevent Home and page sections from rerendering on theme changes
• memoize the theme context value and callbacks
• remove the global transition applied to every element
• fix the Stellar wallet server/client hydration mismatch
• remove the redundant wallet Suspense boundary

Why

Previously, page.tsx consumed ThemeContext directly. Every theme or
custom-color update therefore rerendered the entire page.

The wallet section also checked typeof window during render, causing the
server and client to produce different initial markup.

Verification

• React DevTools Profiler confirms that Home no longer rerenders when changing themes
• theme colors update through the document class and CSS variables
• no hydration errors after reloading the page
• npm test — 16 tests passed
• npm run lint — passed
• npx tsc --noEmit — passed
• npm run build — passed