Missing vite as optional peer dependency

### Reproduction

https://github.com/ForgottenR/vue-router-showcase

### Steps to reproduce the bug

Clone https://github.com/ForgottenR/vue-router-showcase, run `pnpm install`, and then run `pnpm typecheck` from inside the `app` directory.

Note: The `main` branch shows a typical typecheck error that may happen in a mono repo. But the error requires the hoisted package to have a specific layout, which is not stable and doesn't always happen (should happen if `node_modules` folders are all newly created though). The `non-hoisted` branch uses a more strict pnpm setting with `hoisted: false` which doesn't need the hoisted package confliction and is more clear on the root cause.

### Expected behavior

There should be no type errors.

### Actual behavior

A type error similar to the following

`main` branch:
```
$ pnpm typecheck
$ tsc index.ts --noEmit
index.ts:4:5 - error TS2322: Type 'Plugin<any> | Plugin<any>[]' is not assignable to type 'PluginOption'.
  Type 'Plugin<any>' is not assignable to type 'PluginOption'.
    Type 'import("/Users/huijieshi/workspace/vue-router-showcase/node_modules/.pnpm/vite@8.0.12_@types+node@25.6.2_yaml@2.8.4/node_modules/vite/dist/node/index").Plugin<any>' is not assignable to type 'import("/Users/huijieshi/workspace/vue-router-showcase/node_modules/.pnpm/vite@6.4.2_@types+node@25.6.2_lightningcss@1.32.0_yaml@2.8.4/node_modules/vite/dist/node/index").Plugin<any>'.
      Types of property 'hotUpdate' are incompatible.
        Type 'ObjectHook<(this: MinimalPluginContext & { environment: DevEnvironment; }, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<...>> | undefined' is not assignable to type 'ObjectHook<(this: HotUpdatePluginContext, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<void | EnvironmentModuleNode[]>> | undefined'.
          Type '(this: MinimalPluginContext & { environment: DevEnvironment; }, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<...>' is not assignable to type 'ObjectHook<(this: HotUpdatePluginContext, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<void | EnvironmentModuleNode[]>> | undefined'.
            Type '(this: MinimalPluginContext & { environment: DevEnvironment; }, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<...>' is not assignable to type '(this: HotUpdatePluginContext, options: HotUpdateOptions) => void | EnvironmentModuleNode[] | Promise<void | EnvironmentModuleNode[]>'.
              The 'this' types of each signature are incompatible.
                Type 'HotUpdatePluginContext' is not assignable to type 'MinimalPluginContext & { environment: DevEnvironment; }'.
                  Type 'HotUpdatePluginContext' is missing the following properties from type 'MinimalPluginContext': error, info, warn, debug, meta

4 let plugin: PluginOption = VueRouter();
      ~~~~~~


Found 1 error in index.ts:4

[ELIFECYCLE] Command failed with exit code 2.
```
`non-hoisted` branch:
```
$ pnpm typecheck
$ tsc index.ts --noEmit
../node_modules/.pnpm/@vue+compiler-core@3.5.34/node_modules/@vue/compiler-core/dist/compiler-core.d.ts:3:127 - error TS2307: Cannot find module '@babel/types' or its corresponding type declarations.

3 import { Node as Node$1, Identifier, Function, ObjectProperty, BlockStatement as BlockStatement$1, SwitchCase, Program } from '@babel/types';
                                                                                                                                ~~~~~~~~~~~~~~

../node_modules/.pnpm/vue-router@5.0.6_@vue+compiler-sfc@3.5.34_vue@3.5.34_typescript@6.0.3_/node_modules/vue-router/dist/unplugin/vite.d.mts:7:24 - error TS2307: Cannot find module 'vite' or its corresponding type declarations.

7 import * as vite0 from "vite";
                         ~~~~~~


Found 2 errors in 2 files.

Errors  Files
     1  ../node_modules/.pnpm/@vue+compiler-core@3.5.34/node_modules/@vue/compiler-core/dist/compiler-core.d.ts:3
     1  ../node_modules/.pnpm/vue-router@5.0.6_@vue+compiler-sfc@3.5.34_vue@3.5.34_typescript@6.0.3_/node_modules/vue-router/dist/unplugin/vite.d.mts:7
[ELIFECYCLE] Command failed with exit code 2.
```

### Additional information

The root cause of this issue is that in a strict package manager like pnpm, the missing peer dependency declaration would make there no `vite` package to be found in the `node_module` hirarchy from the point of view of the `vue-router` pakackage, thus the `Plugin` type from `vite` cannot be resolved, or resolved to the wrong version sometimes depending on the structure of the pnpm workspace. 

It tends to happen only in a mono repo because in a normal repo, the `vite` package is almost always at the root `node_modules`.

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