feat: add source-only HEIC/HEIF image converter

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/converters/heic.js

@@ -0,0 +1,43 @@
+import fs from 'node:fs/promises';
+import sharp from 'sharp';
+import convert from 'heic-convert';
+import { register } from './registry.js';
+import { sharpFormatName, buildFormatOptions } from './image.js';
+import { encodeIcoFromInput, DEFAULT_ICON_SIZE } from './ico.js';
+
+const IMAGE_FORMATS = ['jpg', 'jpeg', 'png', 'webp', 'gif', 'tiff', 'avif'];
+const HEIC_SOURCE_FORMATS = ['heic', 'heif'];
+
+async function decodeToPng(inputPath) {
+  const buffer = await fs.readFile(inputPath);
+  return convert({ buffer, format: 'PNG' });
+}
+
+export function registerHeicConverter() {
+  for (const sourceFormat of HEIC_SOURCE_FORMATS) {
+    for (const targetFormat of IMAGE_FORMATS) {
+      register({
+        family: 'image',
+        sourceFormat,
+        targetFormat,
+        convert: async (inputPath, outputPath, { quality } = {}) => {
+          const pngBuffer = await decodeToPng(inputPath);
+          await sharp(pngBuffer)
+            .toFormat(sharpFormatName(targetFormat), buildFormatOptions(targetFormat, quality))
+            .toFile(outputPath);
+        },
+      });
+    }
+
+    register({
+      family: 'image',
+      sourceFormat,
+      targetFormat: 'ico',
+      convert: async (inputPath, outputPath, { iconSize } = {}) => {
+        const pngBuffer = await decodeToPng(inputPath);
+        const icoBuffer = await encodeIcoFromInput(pngBuffer, iconSize ?? DEFAULT_ICON_SIZE);
+        await fs.writeFile(outputPath, icoBuffer);
+      },
+    });
+  }
+}