style: badges centered to flags, wider dashboard, mobile header actions

MatchCard:
- Badges (group, countdown, LIVE, BEENDET) now vertically centered
  to flag height, positioned left/right of the teams
- Removed separate topRow — all in one matchBlock flex layout

Dashboard:
- max-width increased to 800px (matches spielplan width)

Header:
- Theme toggle + admin link moved to headerActions (always visible)
- Theme toggle icon in gold color (was too dark in dark mode)
- Admin link brighter (text-secondary instead of text-muted)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/DashboardPage.module.css

@@ -1,6 +1,6 @@
 .dashboard {
-  padding: 16px;
-  max-width: 600px;
+  padding: 12px;
+  max-width: 800px;
   margin: 0 auto;
   display: flex;
   flex-direction: column;