chore: drop vite-tsconfig-paths in favor of Vite 8 native support

Vite 8 added native tsconfig paths resolution via the
`resolve.tsconfigPaths` option, making the `vite-tsconfig-paths` plugin
redundant. After bumping to Vite 8 (#351), running typecheck surfaced
this deprecation hint:

  The plugin "vite-tsconfig-paths" is detected. Vite now supports
  tsconfig paths resolution natively via the resolve.tsconfigPaths
  option. You can remove the plugin and set resolve.tsconfigPaths: true
  in your Vite config instead.

Verified locally: lint, typecheck, all 63 tests pass; dev server boots
and `/de` renders correctly (path imports like `~/utils/...` continue
to resolve).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: HerrBertling

package-lock.json

@@ -55,7 +55,6 @@
     "postcss": "^8.5.14",
     "typescript": "^5.1.6",
     "vite": "^8.0.11",
-    "vite-tsconfig-paths": "^6.1.1",
     "vitest": "^4.1.0"
   },
   "engines": {

package.json

@@ -1,8 +1,10 @@
 import netlifyPlugin from "@netlify/vite-plugin-react-router";
 import { reactRouter } from "@react-router/dev/vite";
 import { defineConfig } from "vite";
-import tsconfigPaths from "vite-tsconfig-paths";
 
 export default defineConfig({
-  plugins: [reactRouter(), netlifyPlugin(), tsconfigPaths()],
+  plugins: [reactRouter(), netlifyPlugin()],
+  resolve: {
+    tsconfigPaths: true,
+  },
 });