Faza 7: White-label per tenant — logo + theme color dinamic

- spatie/laravel-medialibrary instalat (migration media table)
- filament/spatie-laravel-media-library-plugin
- Company implements HasMedia + InteractsWithMedia
  - collections: 'logo' + 'favicon' (singleFile)
  - getLogoUrl() / getFaviconUrl() helpers
- Settings page extins: secțiune Logo & favicon cu FileUpload
  - On save: clear collection + addMedia from temp upload + cleanup tmp file
- TenantPanelProvider render hooks:
  - HEAD_END: theme-color meta + favicon + CSS vars override
    (--primary-50 → --primary-950 generate din hex theme_color)
  - SIDEBAR_LOGO_BEFORE: afișare logo upload-uit, max-height 56px

Cum funcționează:
- Tenant uploadează logo în Settings
- La fiecare request, render hook injectează <style> cu CSS vars custom
- Filament respectă --primary-* → toate butoanele/badge-urile primesc culoarea brand
- Logo apare deasupra meniului (sidebar)

composer.json

@@ -8,11 +8,13 @@
     "require": {
         "php": "^8.2",
         "filament/filament": "^5.6",
+        "filament/spatie-laravel-media-library-plugin": "^5.6",
         "laravel/framework": "^12.0",
         "laravel/octane": "^2.17",
         "laravel/sanctum": "^4.3",
         "laravel/tinker": "^2.10.1",
         "spatie/laravel-activitylog": "^5.0",
+        "spatie/laravel-medialibrary": "^11.22",
         "spatie/laravel-permission": "^7.4",
         "stancl/tenancy": "^3.10"
     },