feat: add badge support to NavItem component (#8207)

## Summary

Adds optional badge support to the `NavItem` component and `NavItemData`
interface, enabling navigation items in the left sidebar of the Asset
Browser Modal to display counts or status indicators.

## Changes

- **`src/types/navTypes.ts`**: Added optional `badge?: string | number`
property to `NavItemData` interface
- **`src/components/widget/nav/NavItem.vue`**: Added `StatusBadge`
rendering when `badge` prop is provided
- **`src/components/widget/panel/LeftSidePanel.vue`**: Wired `badge`
prop from `NavItemData` to `NavItem` for both grouped and ungrouped
items

## Usage

```ts
const navItem: NavItemData = {
  id: 'assets',
  label: 'Assets',
  icon: 'pi pi-folder',
  badge: 5  // Optional - displays count badge
}
```

## Related

- Builds on #8170 which added queue badge functionality

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8207-feat-add-badge-support-to-NavItem-component-2ef6d73d365081669f86fe2fc618e87f)
by [Unito](https://www.unito.io)

src/components/widget/panel/LeftSidePanel.vue

@@ -22,6 +22,7 @@
               v-for="subItem in item.items"
               :key="subItem.id"
               :icon="subItem.icon"
+              :badge="subItem.badge"
               :active="activeItem === subItem.id"
               @click="activeItem = subItem.id"
             >
@@ -32,6 +33,7 @@
         <div v-else class="flex flex-col gap-2">
           <NavItem
             :icon="item.icon"
+            :badge="item.badge"
             :active="activeItem === item.id"
             @click="activeItem = item.id"
           >