refactor: remove global state from fs module and use dispatcher

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

main.c

@@ -130,7 +130,7 @@ int main(int argc, char *argv[]) {
     free(initial_state);
     
     // Initialize filesystem module (auto-save thread)
-    fs_init(initial_state);
+    fs_init();
     
     // Initialize engine
     if (engine_init(&engine, client_name, dispatch) != 0) {