feat: improve test reliability and add request tracing

- Add retry configuration for flaky tests (2 retries for default, 3 for
OAuth)
- Configure test groups with proper concurrency limits (serial: 1,
integration: 4)
- Add tower-http tracing layer with custom span formatting for HTTP
requests
- Simplify database pool handling by removing unnecessary Arc wrapper
- Improve test context setup with better logging and error handling
- Refactor user creation parameters for better clarity and consistency
- Add debug logging for OAuth cookie handling

pacman-server/src/data/user.rs

@@ -68,10 +68,10 @@ pub async fn link_oauth_account(
 
 pub async fn create_user(
     pool: &sqlx::PgPool,
-    username: &str,
-    display_name: Option<&str>,
-    email: Option<&str>,
-    avatar_url: Option<&str>,
+    provider_username: &str,
+    provider_display_name: Option<&str>,
+    provider_email: Option<&str>,
+    provider_avatar_url: Option<&str>,
     provider: &str,
     provider_user_id: &str,
 ) -> Result<User, sqlx::Error> {
@@ -82,20 +82,20 @@ pub async fn create_user(
         RETURNING id, email, created_at, updated_at
         "#,
     )
-    .bind(email)
+    .bind(provider_email)
     .fetch_one(pool)
     .await?;
 
     // Create oauth link
-    let _ = link_oauth_account(
+    let _linked = link_oauth_account(
         pool,
         user.id,
         provider,
         provider_user_id,
-        email,
-        Some(username),
-        display_name,
-        avatar_url,
+        provider_email,
+        Some(provider_username),
+        provider_display_name,
+        provider_avatar_url,
     )
     .await?;