refactor: modularize api server assets and handlers

server-rs/crates/api-server/src/main.rs

@@ -35,6 +35,7 @@ mod custom_world_foundation_draft;
 mod custom_world_result_prompts;
 mod custom_world_rpg_draft_prompts;
 mod error_middleware;
+mod generated_image_assets;
 mod health;
 mod http_error;
 mod hyper3d_generation;
@@ -44,6 +45,7 @@ mod login_options;
 mod logout;
 mod logout_all;
 mod match3d;
+mod modules;
 mod openai_image_generation;
 mod password_entry;
 mod password_management;