Central panel SaaS upgrade — Plans/Subscriptions/SuperAdmins/Detail page

Models & migrations:
- subscriptions table (company, plan, period, amount, status, dates, invoice)
- super_admins: role enum (owner/admin/support/sales/finance) + phone + notes
- Subscription model with STATUSES/PERIODS/PAYMENT_METHODS + invoice number
  generator + extends company.active_until on mark_paid
- Company model: subscriptions() + latestSubscription() relations
- SuperAdmin model: role helpers (isOwner, canManageBilling, canManageTenants)

Filament Central panel:
- PlanResource (CRUD, features checklist, limits per plan, abonati count badge)
- SubscriptionResource (CRUD, mark_paid action, navigation badge for overdue)
- SuperAdminResource (CRUD, reset password, toggle 2FA, can't self-delete)
- ViewCompany page with live stats (users/clients/vehicles/WO/parts/revenue/
  storage/last_login + days_until_expiry), subscriptions history table,
  config snapshot, action buttons (open/issue invoice/upload logo/suspend)
- CompanyResource: row click → view, openUrlInNewTab action, recordTitleAttribute,
  empty state, view route registered
- PlatformStats widget upgraded: 6 cards (incl. MRR realized this month, overdue
  invoices count, click-through to filtered tables)
- RevenueChart: 12-month MRR line chart
- RecentTenants: latest 8 tenants with click-through
- PendingPayments: pending+overdue invoices table
- Database notifications enabled + Cmd+K global search
- HEAD_END render hook: PWA manifest + theme color + emoji favicon
- /admin-manifest.json route

Seeder:
- Plans aligned with new FEATURE_OPTIONS (kanban/pdf/reports/ai/api/reverb/etc)
- 4 plans: Free / Basic / Pro / Enterprise (with proper limits)
- SuperAdmin gets role='owner'
- Demo subscription for psauto on Pro plan, marked paid this month

app/Filament/Central/Widgets/PendingPayments.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Filament\Central\Widgets;
+
+use App\Filament\Central\Resources\SubscriptionResource;
+use App\Models\Central\Subscription;
+use Filament\Tables;
+use Filament\Tables\Table;
+use Filament\Widgets\TableWidget as BaseWidget;
+
+class PendingPayments extends BaseWidget
+{
+    protected static ?int $sort = 4;
+
+    protected int|string|array $columnSpan = 'full';
+
+    public function table(Table $table): Table
+    {
+        return $table
+            ->heading('Facturi pending / overdue')
+            ->query(
+                Subscription::query()
+                    ->whereIn('status', ['pending', 'overdue'])
+                    ->with(['company', 'plan'])
+                    ->latest('due_at')
+                    ->limit(10)
+            )
+            ->columns([
+                Tables\Columns\TextColumn::make('invoice_number')
+                    ->label('Factură')
+                    ->copyable()
+                    ->url(fn ($r) => SubscriptionResource::getUrl('edit', ['record' => $r])),
+                Tables\Columns\TextColumn::make('company.name')->label('Companie'),
+                Tables\Columns\TextColumn::make('plan.name')->placeholder('—'),
+                Tables\Columns\TextColumn::make('amount')->money(fn ($r) => $r->currency)->weight('bold'),
+                Tables\Columns\TextColumn::make('status')
+                    ->badge()
+                    ->color(fn ($s) => $s === 'overdue' ? 'danger' : 'warning')
+                    ->formatStateUsing(fn ($s) => Subscription::STATUSES[$s] ?? $s),
+                Tables\Columns\TextColumn::make('due_at')
+                    ->label('Scadent')
+                    ->dateTime()
+                    ->color(fn ($r) => $r->due_at && $r->due_at->isPast() ? 'danger' : null),
+            ])
+            ->emptyStateHeading('🎉 Toate facturile sunt plătite')
+            ->paginated(false);
+    }
+}