fix: stop emitting the envFile deprecation warning on Vite 8 (#266)

The vite-node server passes `envFile: false` to `createServer`, which Vite 8
deprecated in favour of `envDir: false`. Pick the key from the installed Vite
major so Vite 8 stops warning while the `>=5` peers keep the old key.

Also reformats `packages/react-router-devtools/package.json`, which the
release bot rewrote in becd7c9 without the Validation Pipeline running. That
left `biome ci` failing on main, so every PR since inherits a red check.

Author: bravo-kernel

.changeset/vite8-envfile-deprecation.md

@@ -0,0 +1,7 @@
+---
+"react-router-devtools": patch
+---
+
+Stop emitting the `envFile` deprecation warning on Vite 8.
+
+The internal vite-node server passes `envFile: false` to `createServer`, which Vite 8 deprecated in favour of `envDir: false`. Every Vite 8 consumer therefore saw `The 'envFile' option is deprecated, please use 'envDir: false' instead.` on startup, because the warning is emitted from a top-level `createServer` call that no user config can reach. The key is now chosen from the installed Vite major, so Vite 8 gets `envDir: false` while the existing `>=5` peers keep `envFile: false`.

packages/react-router-devtools/src/vite/node-server.ts

@@ -3,6 +3,8 @@ import { ViteNodeRunner } from "vite-node/client"
 import { ViteNodeServer } from "vite-node/server"
 import { installSourcemapsSupport } from "vite-node/source-map"
 
+const viteMajor = Number(viteVersion.split(".")[0])
+
 // create vite server
 const server = await createServer({
 	mode: "development",
@@ -17,11 +19,14 @@ const server = await createServer({
 		noDiscovery: true,
 	},
 	configFile: false,
-	envFile: false,
+	// Vite 8 deprecated `envFile` in favour of `envDir: false` and warns when
+	// it is passed. Older peers (>=5) only understand `envFile`, so pick the
+	// key the installed Vite expects.
+	...(viteMajor >= 8 ? ({ envDir: false } as const) : ({ envFile: false } as const)),
 	plugins: [],
 })
 // For old Vite, this is need to initialize the plugins.
-if (Number(viteVersion.split(".")[0]) < 6) {
+if (viteMajor < 6) {
 	await server.pluginContainer.buildStart({})
 }