Fix GitHub bot avatar URL (#55297)

## Summary

- Fix GitHub avatar URL generation for bot noreply commit authors
- Fall back to the GitHub commit author API when the CDN email avatar
endpoint cannot resolve bot noreply emails
- Add tests covering bot noreply and regular user noreply author emails

- Before 
<img width="305" height="117" alt="image"
src="https://github.com/user-attachments/assets/01f79e6c-cae6-4c28-a3e3-3ca506898f4f"
/>
- After
<img width="297" height="105" alt="image"
src="https://github.com/user-attachments/assets/3f387b62-e34a-41f5-b377-2afe2e895bf8"
/>


## Test Plan

- `cargo test -p git_hosting_providers --features gpui/test-support`


Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- Fixed GitHub avatar lookup for bot noreply commit authors.

---------

Co-authored-by: Christopher Biscardi <chris@christopherbiscardi.com>

crates/git_hosting_providers/src/providers/github.rs

@@ -68,8 +68,12 @@ pub struct Github {
     base_url: Url,
 }
 
+fn normalize_author_email(email: &str) -> &str {
+    email.trim_start_matches('<').trim_end_matches('>')
+}
+
 fn build_cdn_avatar_url(email: &str) -> Result<Url> {
-    let email = email.trim_start_matches('<').trim_end_matches('>');
+    let email = normalize_author_email(email);
     Url::parse(&format!(
         "https://avatars.githubusercontent.com/u/e?email={}&s=128",
         encode(email)
@@ -77,6 +81,15 @@ fn build_cdn_avatar_url(email: &str) -> Result<Url> {
     .context("failed to construct avatar URL")
 }
 
+fn build_cdn_avatar_url_for_author_email(email: &str) -> Result<Option<Url>> {
+    let email = normalize_author_email(email);
+    if email.ends_with("[bot]@users.noreply.github.com") {
+        return Ok(None);
+    }
+
+    build_cdn_avatar_url(email).map(Some)
+}
+
 impl Github {
     pub fn new(name: impl Into<String>, base_url: Url) -> Self {
         Self {
@@ -267,8 +280,10 @@ impl GitHostingProvider for Github {
         author_email: Option<SharedString>,
         http_client: Arc<dyn HttpClient>,
     ) -> Result<Option<Url>> {
-        if let Some(email) = author_email {
-            return Ok(Some(build_cdn_avatar_url(&email)?));
+        if let Some(email) = author_email
+            && let Some(avatar_url) = build_cdn_avatar_url_for_author_email(&email)?
+        {
+            return Ok(Some(avatar_url));
         }
 
         let commit = commit.to_string();
@@ -629,4 +644,26 @@ mod tests {
             "https://avatars.githubusercontent.com/u/e?email=user%2Btag%40example.com&s=128"
         );
     }
+
+    #[test]
+    fn test_build_cdn_avatar_url_for_author_email_skips_bot_noreply_emails() {
+        for email in [
+            "41898282+github-actions[bot]@users.noreply.github.com",
+            "<41898282+github-actions[bot]@users.noreply.github.com>",
+        ] {
+            assert_eq!(build_cdn_avatar_url_for_author_email(email).unwrap(), None);
+        }
+    }
+
+    #[test]
+    fn test_build_cdn_avatar_url_for_author_email_uses_user_noreply_emails() {
+        let url = build_cdn_avatar_url_for_author_email("12345+octocat@users.noreply.github.com")
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(
+            url.as_str(),
+            "https://avatars.githubusercontent.com/u/e?email=12345%2Boctocat%40users.noreply.github.com&s=128"
+        );
+    }
 }