feat: add ico MIME type and heif->heic extension alias

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

test/mime.test.js

@@ -28,6 +28,12 @@ describe('outputMimeType', () => {
   });
 });
 
+describe('outputMimeType — ico', () => {
+  it('returns image/x-icon for ico', () => {
+    expect(outputMimeType('ico')).toBe('image/x-icon');
+  });
+});
+
 describe('resolveInputFormat', () => {
   it('accepts a PNG file declared as png', async () => {
     const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample.png');
@@ -84,3 +90,17 @@ describe('resolveInputFormat', () => {
     await fs.unlink(fixturePath);
   });
 });
+
+describe('resolveInputFormat — heic/heif alias', () => {
+  it('accepts a HEIC-family file declared as heic', async () => {
+    const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample.heic');
+    const result = await resolveInputFormat(fixturePath, 'heic');
+    expect(result.valid).toBe(true);
+  });
+
+  it('accepts the same HEIC-family content declared as heif', async () => {
+    const fixturePath = path.join(import.meta.dirname, 'fixtures', 'sample.heif');
+    const result = await resolveInputFormat(fixturePath, 'heif');
+    expect(result.valid).toBe(true);
+  });
+});