feat: implement contact form submission and database integration

- Added a new collection for contact submissions with validation and error handling.
- Created a migration script to set up the contact submissions table in the database.
- Updated the SponsoringForm component to handle newsletter subscriptions based on application phase.
- Refactored the UI components for improved user experience and error messaging.
- Removed the package selection step from the sponsoring form.
- Updated the styling across various pages to maintain consistency with the new design.

src/spa/pages/Contact.tsx

@@ -11,7 +11,7 @@ import { contactContent } from '@/spa/contactContent';
 
 const NAVY  = '#111D55';
 const GOLD  = '#EFBF04';
-const CREAM = '#EFE5E3';
+const WHITE = '#fff';
 const INK   = '#3A3A3A';
 
 type ContactCms = NonNullable<Page['contact']>;
@@ -53,7 +53,7 @@ const Contact: React.FC = () => {
   const faqItems = fallbackArray<FaqItem>(faq.items, contactContent.faq.items);
 
   return (
-    <div style={{ background: CREAM }}>
+    <div style={{ background: WHITE }}>
 
       {/* ── Hero ───────────────────────────────────────────────────────── */}
       <section style={{ position: 'relative', height: '68vh', minHeight: 520, overflow: 'hidden', display: 'flex', alignItems: 'flex-end' }}>
@@ -210,7 +210,7 @@ const Contact: React.FC = () => {
       </section>
 
       {/* ── FAQ ────────────────────────────────────────────────────────── */}
-      <section id="faq" style={{ background: CREAM, padding: isMobile ? '56px 0 72px' : '96px 0 112px' }}>
+      <section id="faq" style={{ background: WHITE, padding: isMobile ? '56px 0 72px' : '96px 0 112px' }}>
         <div className="container mx-auto px-6">
           <div style={{ display: 'grid', gridTemplateColumns: isMobile ? '1fr' : '1fr 2fr', gap: isMobile ? 40 : 80 }}>