build(vite): resolve @/ alias in main + preload configs

The four renderer vite configs all resolve "@" to ./src; main and preload
didn't, so any main-reachable file using @/ imports would break the
bundle. Mirror the same alias block in both configs and revert
lib/errors.ts + src/main/* to the project's @/ convention.

js/src/main/ipc-utils.ts

@@ -1,5 +1,5 @@
 import { ipcMain, type IpcMainInvokeEvent } from "electron";
-import { reportError } from "../lib/errors";
+import { reportError } from "@/lib/errors";
 
 type InvokeHandler = (
   event: IpcMainInvokeEvent,