feat(developers): add developer program signup with SilverDESK integration

Add developer application page with form submission that creates tickets
in SilverDESK. Includes provisioning service scaffolding for Mattermost,
Mailcow, and Gitea account creation. Fixes API key header casing
(X-API-Key) and ticket payload to match SilverDESK's CreateTicketDto
contract.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

BlazorApp/Components/Pages/Home.razor

@@ -12,7 +12,7 @@
         <p class="subtitle">Your Innovation Gateway</p>
 
         <div class="gateway-grid">
-            <a href="https://helpdesk.silverlabs.uk" class="gateway-card">
+            <a href="https://silverdesk.silverlabs.uk" class="gateway-card">
                 <div class="card-icon">
                     <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
                         <circle cx="12" cy="12" r="10"></circle>
@@ -57,6 +57,19 @@
                 <h2 class="card-title">SDK</h2>
                 <p class="card-description">Developer Resources</p>
             </a>
+
+            <a href="/developers" class="gateway-card">
+                <div class="card-icon">
+                    <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                        <path d="M17 21v-2a4 4 0 0 0-4-4H5a4 4 0 0 0-4 4v2"></path>
+                        <circle cx="9" cy="7" r="4"></circle>
+                        <path d="M23 21v-2a4 4 0 0 0-3-3.87"></path>
+                        <path d="M16 3.13a4 4 0 0 1 0 7.75"></path>
+                    </svg>
+                </div>
+                <h2 class="card-title">Developers</h2>
+                <p class="card-description">Join the Team</p>
+            </a>
         </div>
     </main>