perf: enable Next.js image optimization and compress images

## Description
Currently, image optimization is disabled in the project, causing poor performance.

## Problems Found
1. `next.config.js` has `unoptimized: true` - disables built-in Next.js image optimization
2. `app/assets/resonate_app.png` is **2.8MB** - should be compressed/WebP
3. Multiple components use native `` tags instead of `next/image`
4. Large PNG files not converted to WebP format

## Expected Behavior
- Use `next/image` component throughout the site
- Convert images to WebP format
- Enable built-in image optimization pipeline
- Target: reduce hero image from 2.8MB to <500KB

## Files to Modify
- `next.config.js` - remove `unoptimized: true`
- `app/assets/resonate_app.png` - convert to WebP
- `app/components/Features/Features.jsx`
- `app/components/TechStack/TechStack.jsx`
- `app/components/About/About.jsx`
- `app/components/Layout/NavBar/index.jsx`
- `app/components/DownloadApp/DownloadApp.jsx`

## Motivation
Image optimization can improve page load time by 50%+ and significantly boost Core Web Vitals scores (LCP, CLS).