tombstone gate all user paths; cleanup deletes late follower rows; spa self-delete to /; adr 0016 + purge comment

crates/adapters/sqlite/src/repositories/account_purge/mod.rs

@@ -223,6 +223,16 @@ impl AccountPurger for SqliteAccountPurger {
                 .execute(&mut *tx)
                 .await
                 .map_err(map_sqlx_error)?;
+            // A Follow arriving on the shared inbox after the purge can leave
+            // a late row for the tombstone; delete it explicitly rather than
+            // rely on the foreign-key cascade of the final `users` delete.
+            for table in ["ap_followers", "ap_following"] {
+                sqlx::query(&format!("DELETE FROM {table} WHERE local_user_id = ?"))
+                    .bind(id)
+                    .execute(&mut *tx)
+                    .await
+                    .map_err(map_sqlx_error)?;
+            }
             for table in RETAINED_USER_TABLES {
                 sqlx::query(&format!("DELETE FROM {table} WHERE user_id = ?"))
                     .bind(id)