perf: speed up build-fonts script (#11196)

**Related Issue:** N/A

## Summary

This significantly improves performance by switching the script to a
Node-based implementation.

#10996
unintentionally introduced significant slowdown on macOS when running
builds at the monorepo level or within the `calcite-ui-icons` package.

packages/calcite-ui-icons/bin/build-fonts.js

@@ -0,0 +1,78 @@
+#!/usr/bin/env node
+const { execSync } = require('child_process');
+const {
+        readdirSync,
+        mkdirSync,
+        rmSync,
+        existsSync,
+        lstatSync,
+        symlinkSync,
+        unlinkSync,
+        readFileSync,
+        writeFileSync,
+      } = require('fs');
+const { join, basename } = require('path');
+const prettier = require('@prettier/sync');
+
+const SCRIPT_DIR = __dirname;
+const PACKAGE_ROOT = join(SCRIPT_DIR, '..');
+const fontsDir = join(PACKAGE_ROOT, 'fonts/icons');
+const iconsDir = join(PACKAGE_ROOT, 'icons');
+
+const sizes = [16, 24, 32];
+const ensureDir = (dir) => mkdirSync(dir, { recursive: true });
+const clearAndPrepareDirs = () => {
+  if (existsSync(fontsDir)) {
+    rmSync(fontsDir, { recursive: true, force: true });
+  }
+  sizes.forEach((size) => ensureDir(join(fontsDir, size.toString())));
+};
+
+const filterIcons = () =>
+  readdirSync(iconsDir).filter((file) => {
+    const filePath = join(iconsDir, file);
+    return file.endsWith('.svg') && !readFileSync(filePath, 'utf8').includes('opacity');
+  });
+
+const createLinks = (icons) => {
+  icons.forEach((icon) => {
+    const src = join(iconsDir, icon);
+    const dest = join(fontsDir, basename(icon));
+    symlinkSync(src, dest);
+  });
+};
+
+const organizeIconsBySize = (size) => {
+  const sizeDir = join(fontsDir, size.toString());
+  readdirSync(fontsDir).forEach((file) => {
+    if (file.includes(`-${size}`)) {
+      const src = join(fontsDir, file);
+      const dest = join(sizeDir, file.replace(`-${size}`, ''));
+      if (lstatSync(src).isSymbolicLink()) {
+        if (existsSync(dest)) unlinkSync(dest);
+        symlinkSync(src, dest);
+      }
+    }
+  });
+};
+
+const generateFonts = (size) =>
+  execSync(`fantasticon fonts/icons/${size}/ -n calcite-ui-icons-${size} --normalize true -t ttf -g json -o fonts/`, {
+    stdio: 'inherit',
+  });
+
+const updateConfig = () => {
+  const codepoints = JSON.parse(readFileSync(join(PACKAGE_ROOT, 'fonts/calcite-ui-icons-16.json'), 'utf8'));
+  const config = prettier.format(JSON.stringify({ codepoints }), { parser: 'json' });
+  writeFileSync(join(PACKAGE_ROOT, 'fantasticonrc.json'), config);
+};
+
+const main = () => {
+  clearAndPrepareDirs();
+  createLinks(filterIcons());
+  sizes.forEach(organizeIconsBySize);
+  sizes.forEach(generateFonts);
+  updateConfig();
+};
+
+main();

packages/calcite-ui-icons/package.json

@@ -42,7 +42,7 @@
   "scripts": {
     "build": "node bin/cli.js",
     "postbuild": "npm run build:sprite && npm run build:fonts",
-    "build:fonts": "bin/build-fonts.sh || true",
+    "build:fonts": "bin/build-fonts.js || true",
     "build:sprite": "concurrently npm:build:sprite-*",
     "build:sprite-16": "svgstore -o sprite-16.svg icons/*-16*.svg",
     "build:sprite-24": "svgstore -o sprite-24.svg icons/*-24*.svg",