Optimize logo file sizes to reduce webpack bundle size (#7979)

## Summary
- Optimized 13 logo files, reducing total size by ~560KB
- Converted hylo.svg (321KB) and nim.svg (126KB) to optimized PNGs
(27KB, 13KB)
- Resized oversized images to max 256×256 while preserving aspect ratios
- Optimized SVGs with SVGO where beneficial
- Fixed file permissions (removed execute bits from image files)
- Added comprehensive README.md with optimization guidelines

## Files Changed
- `lib/languages.ts`: Updated references from hylo.svg → hylo.png,
nim.svg → nim.png
- `public/logos/`: Optimized multiple logo files
- `public/logos/README.md`: New optimization guidelines for future logo
additions

## Size Reductions
- hylo.svg → hylo.png: 321KB → 27KB (92% reduction)
- nim.svg → nim.png: 126KB → 13KB (90% reduction)  
- scala.png: 79KB → 14KB (82% reduction)
- haskell.png: 19KB → 6.5KB (66% reduction)
- pony.svg: 53KB → 35KB (34% reduction)
- odin.png: 48KB → 27KB (44% reduction)
- nix.svg: 26KB → 5KB (81% reduction)
- gimple.svg: 21KB → 11KB (48% reduction)
- spice.png: 16KB → 9.3KB (42% reduction)
- hook.png: 14KB → 9.3KB (34% reduction)
- hook-dark.png: 13KB → 9.3KB (28% reduction)

## Test plan
- [x] Verify all logos display correctly in the language selection UI
- [x] Confirm no broken image references
- [x] Check that webpack bundle size warnings are reduced
- [x] Ensure visual quality is acceptable at small icon sizes

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

lib/languages.ts

@@ -493,7 +493,7 @@ const definitions: Record<LanguageKey, LanguageDefinition> = {
         monaco: 'hylo',
         extensions: ['.hylo'],
         alias: [],
-        logoFilename: 'hylo.svg',
+        logoFilename: 'hylo.png',
         logoFilenameDark: null,
         formatter: null,
         previewFilter: null,
@@ -607,7 +607,7 @@ const definitions: Record<LanguageKey, LanguageDefinition> = {
         monaco: 'nim',
         extensions: ['.nim'],
         alias: [],
-        logoFilename: 'nim.svg',
+        logoFilename: 'nim.png',
         logoFilenameDark: null,
         formatter: null,
         previewFilter: null,

public/logos/README.md

@@ -0,0 +1,44 @@
+# Logo Optimization Guidelines
+
+This directory contains logos for programming languages displayed in Compiler Explorer. To maintain fast loading times and reasonable bundle sizes, logos should be optimized before adding them.
+
+## Size Guidelines
+
+- **Target size**: Keep individual logos under 20KB when possible
+- **Maximum dimensions**: 256×256 pixels (preserving aspect ratio)
+- **File formats**: SVG preferred for simple graphics, PNG for complex images
+
+## Optimization Tools & Commands
+
+### PNG Images
+```bash
+# Resize and optimize (preserves aspect ratio)
+convert input.png -resize 256x256> -quality 85 output.png
+
+# Alternative with pngquant for better compression
+pngquant --quality=65-80 --output output.png input.png
+```
+
+### SVG Images
+```bash
+# Optimize with SVGO (install with: npm install -g svgo)
+npx svgo input.svg --output output.svg
+
+# For SVGs with embedded raster data, convert to PNG instead
+convert input.svg -resize 256x256 -quality 85 output.png
+```
+
+## Common Issues
+
+- **Embedded Base64 data in SVGs**: These are usually very large (300KB+). Convert to PNG instead.
+- **Oversized PNGs**: Images over 1000px wide/tall should be resized to 256×256 or smaller.
+- **16-bit PNGs**: Convert to 8-bit with `convert input.png -depth 8 output.png`
+
+## Recent Optimizations
+
+Examples of successful optimizations:
+- `hylo.svg` (321KB) → `hylo.png` (27KB) - 92% reduction
+- `nim.svg` (126KB) → `nim.png` (13KB) - 90% reduction  
+- `scala.png` (79KB) → optimized (14KB) - 82% reduction
+
+Always test that optimized logos look good at small icon sizes (16-32px) in the UI.

webpack.config.esm.ts

@@ -54,7 +54,7 @@ const hasGit = fs.existsSync(path.resolve(__dirname, '.git'));
 // Hack alert: due to a variety of issues, sometimes we need to change
 // the name here. Mostly it's things like webpack changes that affect
 // how minification is done, even though that's supposed not to matter.
-const webpackJsHack = '.v60.';
+const webpackJsHack = '.v61.';
 const plugins: Webpack.WebpackPluginInstance[] = [
     new MonacoEditorWebpackPlugin({
         languages: [