feat: Add proxying support for images (#2427)

- Closes #2418

tests/ha/sign-path.test.ts

@@ -1,5 +1,8 @@
 import { afterEach, describe, expect, it, vi } from 'vitest';
-import { homeAssistantSignPath } from '../../src/ha/sign-path';
+import {
+  homeAssistantGetSignedURLIfNecessary,
+  homeAssistantSignPath,
+} from '../../src/ha/sign-path';
 import { homeAssistantWSRequest } from '../../src/ha/ws-request.js';
 import { signedPathSchema } from '../../src/types';
 import { createHASS } from '../test-utils';
@@ -36,3 +39,52 @@ describe('homeAssistantSignPath', () => {
     expect(await homeAssistantSignPath(createHASS(), 'unsigned/path', 42)).toBeNull();
   });
 });
+
+describe('homeAssistantSignEndpoint', () => {
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return endpoint URL without signing when sign is false', async () => {
+    const endpoint = { endpoint: 'http://example.com', sign: false };
+    expect(await homeAssistantGetSignedURLIfNecessary(createHASS(), endpoint)).toBe(
+      'http://example.com',
+    );
+    expect(homeAssistantWSRequest).not.toHaveBeenCalled();
+  });
+
+  it('should return endpoint URL without signing when sign is undefined', async () => {
+    const endpoint = { endpoint: 'http://example.com' };
+    expect(await homeAssistantGetSignedURLIfNecessary(createHASS(), endpoint)).toBe(
+      'http://example.com',
+    );
+    expect(homeAssistantWSRequest).not.toHaveBeenCalled();
+  });
+
+  it('should sign endpoint when sign is true', async () => {
+    const hass = createHASS();
+    vi.mocked(homeAssistantWSRequest).mockResolvedValue({
+      path: 'signed/path',
+    });
+    vi.mocked(hass.hassUrl).mockImplementation((url) => 'hass:' + url);
+
+    const endpoint = { endpoint: 'http://example.com', sign: true };
+    expect(await homeAssistantGetSignedURLIfNecessary(hass, endpoint, 60)).toBe(
+      'hass:signed/path',
+    );
+    expect(homeAssistantWSRequest).toHaveBeenCalledWith(hass, signedPathSchema, {
+      type: 'auth/sign_path',
+      path: 'http://example.com',
+      expires: 60,
+    });
+  });
+
+  it('should return null when signing fails', async () => {
+    vi.mocked(homeAssistantWSRequest).mockResolvedValue(null);
+
+    const endpoint = { endpoint: 'http://example.com', sign: true };
+    expect(
+      await homeAssistantGetSignedURLIfNecessary(createHASS(), endpoint),
+    ).toBeNull();
+  });
+});