feat: implement advanced analytics for mobile admin dashboard

This commit includes:
- Backend EventAnalyticsService and Controller
- API endpoint for event analytics
- Frontend EventAnalyticsPage with custom bar charts and top contributor lists
- Analytics shortcut on the dashboard
- Feature-lock upsell UI for non-premium users

routes/api.php

@@ -201,6 +201,7 @@ Route::prefix('v1')->name('api.v1.')->group(function () {
         Route::prefix('events/{event:slug}')->scopeBindings()->group(function () {
             Route::middleware('tenant.admin')->group(function () {
                 Route::get('stats', [EventController::class, 'stats'])->name('tenant.events.stats');
+                Route::get('analytics', [\App\Http\Controllers\Api\Tenant\EventAnalyticsController::class, 'show'])->name('tenant.events.analytics');
                 Route::post('toggle', [EventController::class, 'toggle'])->name('tenant.events.toggle');
                 Route::post('invites', [EventController::class, 'createInvite'])->name('tenant.events.invites');
                 Route::get('toolkit', [EventController::class, 'toolkit'])->name('tenant.events.toolkit');