feat: remove start.sh script and add appearance preferences management

- Deleted the start.sh script for container management.
- Added AGENTS.md for project guidelines and development principles.
- Introduced new SQL migration files for user appearance preferences and platform settings.
- Implemented appearance provider to manage user interface themes and preferences.
- Created branding utility to define and manage branding-related constants and types.

Co-authored-by: Copilot <copilot@github.com>

src/app/dashboard/invoices/[id]/page.tsx

@@ -411,7 +411,7 @@ function InvoiceViewContent({ invoiceId }: { invoiceId: string }) {
 
         {/* Right Column - Actions */}
         <div className="space-y-6">
-          <Card className="sticky top-20">
+          <Card className="lg:sticky lg:top-6">
             <CardHeader>
               <CardTitle className="flex items-center gap-2">
                 <Check className="h-5 w-5" />