refactor: separate local voice handlers and instructions

server/providers/common/source-root.js

@@ -0,0 +1,7 @@
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+/** Resolve defaultSourceRoot for ESM context. */
+const defaultSourceRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../../..');
+
+export { defaultSourceRoot };