feat(integrations): support GitHub repositories and enhance repo browser UI

Add GitHub repository support to integrations and update related tests.
Implement server-side GitHub API calls and normalize GitHub base URLs.
Improve the repository browser UI with compact tabs and updated icons.
Add a custom, accessible scrollbar with pointer and keyboard support.

- Add paging, auth headers, and error handling when listing GitHub repos.
- Default GitHub token username to "x-access-token" when saving credentials.
- Introduce compact repo tab styles, new icons, and a draggable scrollbar.

src-tauri/src/integrations.rs

@@ -38,6 +38,24 @@ struct GitLabProject {
     visibility: String,
 }
 
+#[derive(Debug, Deserialize)]
+struct GitHubRepository {
+    id: u64,
+    name: String,
+    full_name: String,
+    #[serde(default)]
+    description: Option<String>,
+    clone_url: String,
+    #[serde(default)]
+    ssh_url: String,
+    #[serde(default)]
+    html_url: String,
+    #[serde(default)]
+    updated_at: String,
+    #[serde(default)]
+    private: bool,
+}
+
 #[derive(Debug, Deserialize)]
 struct GiteaRepository {
     id: u64,
@@ -113,6 +131,14 @@ fn normalized_base_url(base_url: &str) -> Result<String, String> {
     Ok(base_url.to_string())
 }
 
+fn github_api_base_url(base_url: &str) -> Result<String, String> {
+    match normalized_base_url(base_url)?.to_ascii_lowercase().as_str() {
+        "https://github.com" | "https://www.github.com" => Ok("https://api.github.com".to_string()),
+        "https://api.github.com" => Ok("https://api.github.com".to_string()),
+        _ => Err("The GitHub integration URL must be https://github.com.".to_string()),
+    }
+}
+
 fn response_error(response: Response, provider: &str) -> String {
     let status = response.status();
     let detail = response.text().ok().and_then(|body| {
@@ -188,6 +214,57 @@ fn gitlab_repositories(
     Ok(repositories)
 }
 
+fn github_repositories(
+    client: &Client,
+    base_url: &str,
+    token: &str,
+) -> Result<Vec<IntegrationRepository>, String> {
+    let api_base_url = github_api_base_url(base_url)?;
+    let mut repositories = Vec::new();
+    let mut page = 1usize;
+    loop {
+        let response = client
+            .get(format!("{api_base_url}/user/repos"))
+            .header(USER_AGENT, "Gitty")
+            .header(ACCEPT, "application/vnd.github+json")
+            .header("Authorization", format!("Bearer {token}"))
+            .header("X-GitHub-Api-Version", "2026-03-10")
+            .query(&[
+                ("per_page", PAGE_SIZE.to_string()),
+                ("page", page.to_string()),
+                ("sort", "updated".to_string()),
+                ("direction", "desc".to_string()),
+            ])
+            .send()
+            .map_err(|err| format!("Could not reach GitHub: {err}"))?;
+        if !response.status().is_success() {
+            return Err(response_error(response, "GitHub"));
+        }
+        let page_repositories = response
+            .json::<Vec<GitHubRepository>>()
+            .map_err(|err| format!("GitHub returned an unreadable repository list: {err}"))?;
+        let count = page_repositories.len();
+        repositories.extend(page_repositories.into_iter().map(|repository| {
+            IntegrationRepository {
+                id: repository.id.to_string(),
+                name: repository.name,
+                full_name: repository.full_name,
+                description: repository.description.unwrap_or_default(),
+                clone_url: repository.clone_url,
+                ssh_url: repository.ssh_url,
+                web_url: repository.html_url,
+                updated_at: repository.updated_at,
+                private: repository.private,
+            }
+        }));
+        if count < PAGE_SIZE {
+            break;
+        }
+        page += 1;
+    }
+    Ok(repositories)
+}
+
 fn gitea_repositories(
     client: &Client,
     base_url: &str,
@@ -286,6 +363,7 @@ pub async fn list_integration_repositories(
         let base_url = normalized_base_url(&base_url)?;
         let client = client()?;
         match provider.as_str() {
+            "github" => github_repositories(&client, &base_url, &credential.password),
             "gitlab" | "gitlab-self-hosted" => {
                 gitlab_repositories(&client, &base_url, &credential.password)
             }
@@ -318,10 +396,19 @@ mod tests {
             "https://gitlab.example.com"
         );
         assert!(normalized_base_url("gitlab.example.com").is_err());
+        assert_eq!(
+            github_api_base_url("https://github.com/").unwrap(),
+            "https://api.github.com"
+        );
+        assert!(github_api_base_url("https://github.example.com").is_err());
     }
 
     #[test]
     fn integration_credential_keys_match_the_frontend() {
+        assert_eq!(
+            integration_key("github", None).unwrap(),
+            "integration:github"
+        );
         assert_eq!(integration_key("gitea", None).unwrap(), "integration:gitea");
         assert_eq!(
             integration_key("azure-devops", Some("org-123")).unwrap(),
@@ -336,6 +423,13 @@ mod tests {
 
     #[test]
     fn provider_repository_payloads_deserialize() {
+        let github: Vec<GitHubRepository> = serde_json::from_str(
+            r#"[{"id":6,"name":"desktop","full_name":"team/desktop","description":null,"clone_url":"https://github.com/team/desktop.git","ssh_url":"git@github.com:team/desktop.git","html_url":"https://github.com/team/desktop","updated_at":"2026-08-29T09:00:00Z","private":true}]"#,
+        )
+        .unwrap();
+        assert_eq!(github[0].full_name, "team/desktop");
+        assert!(github[0].description.is_none());
+
         let gitlab: Vec<GitLabProject> = serde_json::from_str(
             r#"[{"id":7,"name":"app","path_with_namespace":"team/app","description":"Demo","http_url_to_repo":"https://gitlab.test/team/app.git","ssh_url_to_repo":"git@gitlab.test:team/app.git","web_url":"https://gitlab.test/team/app","last_activity_at":"2026-08-29T10:00:00Z","visibility":"private"}]"#,
         )