feat: Implement basic general folder support (#2051)

- Related: #1748

tests/ha/sign-path.test.ts

@@ -0,0 +1,38 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { homeAssistantSignPath } from '../../src/ha/sign-path';
+import { homeAssistantWSRequest } from '../../src/ha/ws-request.js';
+import { signedPathSchema } from '../../src/types';
+import { createHASS } from '../test-utils';
+
+vi.mock('../../src/ha/ws-request.js');
+
+describe('homeAssistantSignPath', () => {
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should sign path', async () => {
+    const hass = createHASS();
+    const unsignedPath = 'unsigned/path';
+    const expires = 42;
+
+    vi.mocked(homeAssistantWSRequest).mockResolvedValue({
+      path: 'signed/path',
+    });
+    vi.mocked(hass.hassUrl).mockImplementation((url) => 'hass:' + url);
+
+    expect(await homeAssistantSignPath(hass, unsignedPath, expires)).toEqual(
+      'hass:signed/path',
+    );
+    expect(homeAssistantWSRequest).toBeCalledWith(hass, signedPathSchema, {
+      type: 'auth/sign_path',
+      path: unsignedPath,
+      expires,
+    });
+  });
+
+  it('should return null for null response', async () => {
+    vi.mocked(homeAssistantWSRequest).mockResolvedValue(null);
+    expect(await homeAssistantSignPath(createHASS(), 'unsigned/path', 42)).toBeNull();
+  });
+});