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/Resources/SuperAdminResource/Pages/EditSuperAdmin.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace App\Filament\Central\Resources\SuperAdminResource\Pages;
+
+use App\Filament\Central\Resources\SuperAdminResource;
+use Filament\Actions;
+use Filament\Resources\Pages\EditRecord;
+
+class EditSuperAdmin extends EditRecord
+{
+    protected static string $resource = SuperAdminResource::class;
+
+    protected function getHeaderActions(): array
+    {
+        return [Actions\DeleteAction::make()];
+    }
+}