fix vite dev server: bind 127.0.0.1, ignore src-tauri/target

Vite defaulted to an IPv6-only bind, so tauri dev's readiness probe
(which checks 127.0.0.1) waited forever even though Vite was up.
Separately, its file watcher was watching Rust's build output and
crashed on a locked .pdb file mid-compile.

vite.config.ts

@@ -3,8 +3,12 @@ import { defineConfig } from "vite";
 export default defineConfig({
   clearScreen: false,
   server: {
+    host: "127.0.0.1",
     port: 1420,
     strictPort: true,
+    watch: {
+      ignored: ["**/src-tauri/**"],
+    },
   },
   build: {
     target: "es2022",