feat: Implement basic general folder support (#2051)

- Related: #1748

tests/ha/brands-url.test.ts

@@ -0,0 +1,71 @@
+import { describe, expect, it } from 'vitest';
+import {
+  brandsUrl,
+  extractDomainFromBrandUrl,
+  isBrandUrl,
+} from '../../src/ha/brands-url';
+
+describe('brandsUrl', () => {
+  it('generates a basic icon url', () => {
+    expect(brandsUrl({ domain: 'amcrest', type: 'icon' })).toBe(
+      'https://brands.home-assistant.io/amcrest/icon.png',
+    );
+  });
+
+  it('generates a logo url with brand', () => {
+    expect(brandsUrl({ domain: 'hikvision', type: 'logo', brand: true })).toBe(
+      'https://brands.home-assistant.io/brands/hikvision/logo.png',
+    );
+  });
+
+  it('generates a dark optimized icon@2x url with fallback', () => {
+    expect(
+      brandsUrl({
+        domain: 'unifi',
+        type: 'icon@2x',
+        useFallback: true,
+        darkOptimized: true,
+      }),
+    ).toBe('https://brands.home-assistant.io/_/unifi/dark_icon@2x.png');
+  });
+
+  it('generates a logo@2x url with all options', () => {
+    expect(
+      brandsUrl({
+        domain: 'dahua',
+        type: 'logo@2x',
+        useFallback: true,
+        darkOptimized: true,
+        brand: true,
+      }),
+    ).toBe('https://brands.home-assistant.io/brands/_/dahua/dark_logo@2x.png');
+  });
+});
+
+describe('extractDomainFromBrandUrl', () => {
+  it('extracts domain from a brands url', () => {
+    expect(
+      extractDomainFromBrandUrl(
+        'https://brands.home-assistant.io/brands/hikvision/logo.png',
+      ),
+    ).toBe('hikvision');
+  });
+});
+
+describe('isBrandUrl', () => {
+  it('returns true for a valid brands url', () => {
+    expect(isBrandUrl('https://brands.home-assistant.io/amcrest/icon.png')).toBe(true);
+  });
+
+  it('returns false for a non-brands url', () => {
+    expect(isBrandUrl('https://example.com/amcrest/icon.png')).toBe(false);
+  });
+
+  it('returns false for undefined', () => {
+    expect(isBrandUrl(undefined)).toBe(false);
+  });
+
+  it('returns false for null', () => {
+    expect(isBrandUrl(null)).toBe(false);
+  });
+});