Enhance dashboard overview with activity summary and sidebar commands

- Integrated activity summary into the Guild Overview page, displaying message count, voice minutes, and active user count for the last 7 days.
- Updated sidebar to include a new "Commands" link for easier navigation.
- Added corresponding localization keys for activity metrics in both English and German JSON files.

apps/webui/src/components/layout/sidebar.tsx

@@ -1,7 +1,7 @@
 'use client';
 
 import { DASHBOARD_MODULES, type DashboardModuleGroup } from '@nexumi/shared';
-import { LayoutGrid, Settings, ShieldCheck, SlidersHorizontal } from 'lucide-react';
+import { LayoutGrid, Settings, ShieldCheck, SlidersHorizontal, Terminal } from 'lucide-react';
 import Link from 'next/link';
 import { usePathname } from 'next/navigation';
 import { useTranslations } from '@/components/locale-provider';
@@ -64,6 +64,10 @@ export function Sidebar({ guildId }: SidebarProps) {
           <ShieldCheck className="size-4" />
           {t('nav.access')}
         </NavLink>
+        <NavLink href={`${base}/commands`} active={pathname === `${base}/commands`}>
+          <Terminal className="size-4" />
+          {t('nav.commands')}
+        </NavLink>
       </div>
 
       {groups.map(({ group, modules }) => (