feat(i18n): wrap 1103 hardcoded UI strings across Filament with __()

- Convert static $modelLabel/$pluralModelLabel/$title to getter methods
- Wrap ->label()/->placeholder()/->helperText()/->description()/->title()/->body() args
- Wrap Section::make()/Fieldset::make()/Notification::make()->title() args
- Fix RelationManagers::getTitle() signature to match parent (Model, string)
- Fix Pages::getTitle() to instance method (BasePage::getTitle is non-static)
- Extend lang/ru.json + lang/en.json with 700+ common terms; identity fallback for the rest
- Remove duplicate getters in 5 resources that had manual getModelLabel already

All 306 tests pass. Missing translations fall back to the RO key so the UI never breaks.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/Filament/Central/Widgets/PlatformStats.php

@@ -39,7 +39,7 @@ class PlatformStats extends BaseWidget
                 ->color('primary')
                 ->url(\App\Filament\Central\Resources\CompanyResource::getUrl('index')),
             Stat::make('Active', $active)
-                ->description("✓ Pe abonament plătit")
+                ->description(__("✓ Pe abonament plătit"))
                 ->descriptionIcon('heroicon-m-check-circle')
                 ->color('success'),
             Stat::make('În trial', $trial)
@@ -51,7 +51,7 @@ class PlatformStats extends BaseWidget
                 ->descriptionIcon('heroicon-m-exclamation-triangle')
                 ->color($expiring > 0 ? 'danger' : 'success'),
             Stat::make('Venit luna curentă', number_format($mrr, 0, ',', ' ') . ' MDL')
-                ->description('MRR realizat')
+                ->description(__('MRR realizat'))
                 ->descriptionIcon('heroicon-m-banknotes')
                 ->color('success'),
             Stat::make('Facturi neplătite', $overdue)