fix(lint): remove unnecessary async keywords from synchronous functions

- Remove async from functions that don't use await
- Change return types from Promise<void> to void for synchronous functions
- Fixes all 8 require-await lint warnings
- Reduces total lint warnings from 63 to 55

ts/daemon.ts

@@ -196,7 +196,7 @@ export class NupstDaemon {
   /**
    * Save configuration to file
    */
-  public async saveConfig(config: INupstConfig): Promise<void> {
+  public saveConfig(config: INupstConfig): void {
     try {
       const configDir = path.dirname(this.CONFIG_PATH);
       if (!fs.existsSync(configDir)) {