perf: convert all images to webp, update references

- 77 jpg/png/gif → webp (kept 7 where webp larger)
- public/ assets: 23.3 MB → ~12 MB (~50% smaller)
- 110 image references updated across data files + components
- scripts/convert-to-webp.mjs + scripts/fix-image-refs.mjs added

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/convert-to-webp.mjs

@@ -0,0 +1,74 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+import sharp from 'sharp';
+
+const ROOT = path.resolve('public');
+// Files NOT to touch
+const SKIP = new Set(['favicon.ico', 'apple-touch-icon.png', 'icon.png', 'apple-icon.png']);
+const SKIP_EXACT_PATHS = new Set([
+  'public/favicon.ico',
+  'public/apple-touch-icon.png',
+]);
+
+const exts = new Set(['.jpg', '.jpeg', '.png', '.gif']);
+const results = { converted: 0, savedBytes: 0, skipped: 0, failed: 0 };
+
+async function walk(dir) {
+  const entries = await fs.readdir(dir, { withFileTypes: true });
+  for (const e of entries) {
+    const p = path.join(dir, e.name);
+    if (e.isDirectory()) {
+      await walk(p);
+    } else if (exts.has(path.extname(p).toLowerCase())) {
+      await convert(p);
+    }
+  }
+}
+
+async function convert(input) {
+  const ext = path.extname(input).toLowerCase();
+  const base = input.slice(0, -ext.length);
+  const output = base + '.webp';
+  const relRoot = path.relative(process.cwd(), input).split(path.sep).join('/');
+  if (SKIP.has(path.basename(input)) || SKIP_EXACT_PATHS.has(relRoot)) {
+    results.skipped++;
+    console.log(`SKIP   ${relRoot}`);
+    return;
+  }
+  try {
+    const stIn = await fs.stat(input);
+    // Output options per type
+    const isPng = ext === '.png';
+    const isGif = ext === '.gif';
+    const opts = isPng
+      ? { quality: 86, alphaQuality: 90, effort: 5, nearLossless: false }
+      : isGif
+      ? { quality: 80, effort: 5, loop: 0 } // animated -> animated webp
+      : { quality: 82, effort: 5 };
+    let pipeline = sharp(input, { animated: isGif });
+    await pipeline.webp(opts).toFile(output);
+    const stOut = await fs.stat(output);
+    if (stOut.size >= stIn.size) {
+      // worse than original — keep original, remove webp
+      await fs.unlink(output);
+      results.skipped++;
+      console.log(`KEEP   ${relRoot}  (webp larger: ${stOut.size} vs ${stIn.size})`);
+      return;
+    }
+    await fs.unlink(input);
+    results.converted++;
+    results.savedBytes += stIn.size - stOut.size;
+    const inKB = (stIn.size / 1024).toFixed(0);
+    const outKB = (stOut.size / 1024).toFixed(0);
+    console.log(`OK     ${relRoot}  ${inKB}KB -> ${outKB}KB`);
+  } catch (err) {
+    results.failed++;
+    console.log(`FAIL   ${relRoot}: ${err.message}`);
+  }
+}
+
+await walk(ROOT);
+const savedMB = (results.savedBytes / 1024 / 1024).toFixed(2);
+console.log('\n---');
+console.log(`converted: ${results.converted}  skipped: ${results.skipped}  failed: ${results.failed}`);
+console.log(`saved: ${savedMB} MB`);