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/Models/Central/SuperAdmin.php

@@ -19,8 +19,16 @@ class SuperAdmin extends Authenticatable implements FilamentUser, HasAppAuthenti
 
     protected $table = 'super_admins';
 
+    public const ROLES = [
+        'owner' => 'Proprietar (toate drepturile)',
+        'admin' => 'Administrator',
+        'support' => 'Suport (read-only + acces tenanți)',
+        'sales' => 'Vânzări (gestiune Companii + Plans)',
+        'finance' => 'Financiar (Subscriptions + facturi)',
+    ];
+
     protected $fillable = [
-        'name', 'email', 'password', 'is_active', 'last_login_at',
+        'name', 'email', 'phone', 'password', 'is_active', 'role', 'notes', 'last_login_at',
         'email_authentication_at',
         'app_authentication_secret', 'app_authentication_recovery_codes',
     ];
@@ -47,6 +55,11 @@ class SuperAdmin extends Authenticatable implements FilamentUser, HasAppAuthenti
         return $panel->getId() === 'central' && $this->is_active;
     }
 
+    public function isOwner(): bool { return $this->role === 'owner'; }
+    public function isAdmin(): bool { return in_array($this->role, ['owner', 'admin'], true); }
+    public function canManageBilling(): bool { return in_array($this->role, ['owner', 'admin', 'finance'], true); }
+    public function canManageTenants(): bool { return in_array($this->role, ['owner', 'admin', 'sales'], true); }
+
     public function hasEmailAuthentication(): bool
     {
         return $this->email_authentication_at !== null;