Add routed dashboard layout with sidebar

### Motivation
- Provide a multi-tab dashboard layout so users can navigate between logical sections (Dashboard, Players, Graphics, Settings, About) via a persistent sidebar.
- Integrate `vue-router` to manage in-app navigation inside the Quasar layout for a cleaner, scalable dashboard structure.

### Description
- Added `vue-router` as a dev dependency and created `src/dashboard/example/router.ts` with routes for the five views (`/`, `/players`, `/graphics`, `/settings`, `/about`).
- Replaced the example dashboard UI with a Quasar `QLayout` in `src/dashboard/example/main.vue` that includes a left `QDrawer` sidebar and a `RouterView` outlet, and wired the app to the router in `src/dashboard/example/main.ts`.
- Added simple stub views for each tab under `src/dashboard/example/views/` (`Dashboard.vue`, `Players.vue`, `Graphics.vue`, `Settings.vue`, `About.vue`).
- Adjusted `src/dashboard/template.html` to remove the default NodeCG body margin (`margin: 0`) so the layout can occupy the full panel area.

### Testing
- Ran `npm install` which completed and added the new package with audit warnings about vulnerabilities reported. (succeeded)
- Started the dev server with `npx vite` which reported the inputs and served the bundle at `http://localhost:4173/bundles/scoreko-dev/` and `vue-tsc` reported `Found 0 errors` while watching. (succeeded)
- Attempted a Playwright screenshot run to capture the dashboard UI, but the Chromium process crashed (`TargetClosedError` / SIGSEGV) so no screenshot was produced. (failed)

------
[Codex Task](https://chatgpt.com/codex/tasks/task_e_69876e97329c832a8af7179a9175d88b)

src/dashboard/example/main.ts

@@ -5,10 +5,12 @@ import { Dark, Quasar } from 'quasar';
 import 'quasar/src/css/index.sass';
 import { createApp } from 'vue';
 import App from './main.vue';
+import router from './router';
 
 const app = createApp(App);
 const head = createHead();
 app.use(Quasar);
 app.use(head);
+app.use(router);
 app.mount('#app');
 Dark.set(true);