feat: Customize login page with logo, brand name, and tagline

[uzeyirrr]

What is this PR about?

This PR adds whitelabel functionality to customize the login page and onboarding layout with custom logo, brand name, and tagline. Users can now personalize the authentication experience through a dedicated settings page.

Changes Made

Backend

• Added whitelabelLogoUrl, whitelabelBrandName, and whitelabelTagline fields to webServerSettings database schema
• Created updateWhitelabel API endpoint in settings router
• Updated validation schemas to include whitelabel fields

Frontend

• Created new /dashboard/settings/whitelabel page with form component
• Updated OnboardingLayout to use whitelabel settings (logo, brand name, tagline)
• Updated login page to display custom logo
• Added "Whitelabel" menu item to settings sidebar (admin/owner only, non-cloud)
• Added translations for whitelabel settings (English and Turkish)

Features

• Custom Logo: Upload logo via URL to replace default Dokploy logo
• Brand Name: Customize the brand name displayed on login page
• Tagline: Add custom tagline/slogan to the onboarding layout
• Settings Page: Dedicated settings page accessible from Settings > Whitelabel
• Cloud Restriction: Feature is only available for self-hosted installations

Testing

1. Navigate to Settings > Whitelabel
2. Enter logo URL, brand name, and tagline
3. Save settings
4. Log out and verify changes on login page
5. Verify onboarding layout shows custom branding

Checklist

• Database schema updated
• API endpoints created
• Frontend components created
• Translations added
• Cloud environment check implemented

Notes

• Feature is disabled in cloud environments
• Only admin and owner roles can access whitelabel settings
• Logo URL must be a valid URL format
• All fields are optional and nullable
• Database migration required for new fields

[uzeyirrr]

fix: review for whitelabel feature

• Fix hardcoded Turkish text to use translations
• Add database migration for whitelabel fields
• Add translations for all supported languages
• Improve URL validation with HTTPS requirement
• Add input limits and sanitization
• Move whitelabel settings to server-side
• Keep Dokploy credits in onboarding layout