feat: implement automatic image optimization with Astro Assets

- Configure content collections to use image() helper for type-safe image references
- Replace all <img> tags with <Image> component from astro:assets
- Migrate images from /public to /src/assets for automatic optimization
- Update blog posts to use relative paths in frontmatter (../../assets/photos/)
- Remove unused images and duplicates from /public folder
- Update Footer component to use optimized SVG icons
- Clean up manifest.json to use favicon.ico instead of deleted photos

Performance improvements:
- remote.jpg: 1.8MB → 128KB (93% reduction)
- me.png: 71KB → 12KB (83% reduction)
- Automatic WebP conversion
- Tree-shaking: only used images are optimized

/public folder reduced from 2.3MB to 32KB (only essential files)
Build output: 2.2MB with fully optimized images ready for S3 deployment

package.json

@@ -15,8 +15,10 @@
 		"type-check": "astro check"
 	},
 	"dependencies": {
+		"@astrojs/mdx": "^4.3.13",
 		"@astrojs/tailwind": "^6.0.2",
 		"astro": "^5.16.7",
+		"sharp": "^0.34.5",
 		"tailwindcss": "^3.4.0"
 	},
 	"devDependencies": {