feat: add automated PDF invoice generation and storage in Supabase

shop/supabase/migrations/20260430222242_create_invoice_bucket.sql

@@ -0,0 +1,9 @@
+-- Create bucket for invoices
+INSERT INTO storage.buckets (id, name, public) 
+VALUES ('invoices', 'invoices', true)
+ON CONFLICT (id) DO NOTHING;
+
+-- Policies for invoices bucket
+-- Allow public access to invoices (simplified for this demo, usually should be restricted)
+CREATE POLICY "Public Access" ON storage.objects FOR SELECT USING (bucket_id = 'invoices');
+CREATE POLICY "Authenticated Upload" ON storage.objects FOR INSERT WITH CHECK (bucket_id = 'invoices' AND auth.role() = 'authenticated');