Fix avatar display on GitHub Enterprise by passing email to avatar fallback

- Modified parseAccount to pass author.email to getAvatarWithEnterpriseFallback
- Added comprehensive tests for getAvatarWithEnterpriseFallback function
- Tests verify Gravatar fallback works when avatarUrl is empty on Enterprise

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/github/utils.ts

@@ -653,7 +653,7 @@ export function parseAccount(
 
 		// In some places, Copilot comes in as a user, and in others as a bot
 
-		const finalAvatarUrl = githubRepository ? getAvatarWithEnterpriseFallback(avatarUrl, undefined, githubRepository.remote.isEnterprise) : avatarUrl;
+		const finalAvatarUrl = githubRepository ? getAvatarWithEnterpriseFallback(avatarUrl, author.email ?? undefined, githubRepository.remote.isEnterprise) : avatarUrl;
 
 		return {
 			login: author.login,

src/test/github/utils.test.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { default as assert } from 'assert';
-import { getPRFetchQuery, sanitizeIssueTitle } from '../../github/utils';
+import { getPRFetchQuery, sanitizeIssueTitle, getAvatarWithEnterpriseFallback } from '../../github/utils';
 
 describe('utils', () => {
 
@@ -41,4 +41,44 @@ describe('utils', () => {
 			});
 		});
 	});
+
+	describe('getAvatarWithEnterpriseFallback', () => {
+		it('returns avatarUrl for non-enterprise when provided', () => {
+			const avatarUrl = 'https://avatars.githubusercontent.com/u/12345';
+			const result = getAvatarWithEnterpriseFallback(avatarUrl, undefined, false);
+			assert.strictEqual(result, avatarUrl);
+		});
+
+		it('returns avatarUrl for enterprise when avatarUrl is provided', () => {
+			const avatarUrl = 'https://enterprise.github.com/avatars/u/12345';
+			const result = getAvatarWithEnterpriseFallback(avatarUrl, 'user@example.com', true);
+			assert.strictEqual(result, avatarUrl);
+		});
+
+		it('returns Gravatar URL for enterprise when avatarUrl is empty and email is provided', () => {
+			const email = 'user@example.com';
+			const result = getAvatarWithEnterpriseFallback('', email, true);
+			assert.ok(result);
+			assert.ok(result!.startsWith('https://www.gravatar.com/avatar/'));
+			assert.ok(result!.includes('s=200')); // default size
+			assert.ok(result!.includes('d=retro')); // default style
+		});
+
+		it('returns undefined for enterprise when both avatarUrl and email are empty', () => {
+			const result = getAvatarWithEnterpriseFallback('', undefined, true);
+			assert.strictEqual(result, undefined);
+		});
+
+		it('returns avatarUrl for enterprise when avatarUrl has only whitespace', () => {
+			const result = getAvatarWithEnterpriseFallback('   ', 'user@example.com', true);
+			assert.strictEqual(result, undefined);
+		});
+
+		it('generates consistent Gravatar hash for same email', () => {
+			const email = 'test@example.com';
+			const result1 = getAvatarWithEnterpriseFallback('', email, true);
+			const result2 = getAvatarWithEnterpriseFallback('', email, true);
+			assert.strictEqual(result1, result2);
+		});
+	});
 });