Rename MyCrib to Casera in admin test email footer

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/admin/handlers/notification_handler.go

@@ -384,7 +384,7 @@ func (h *AdminNotificationHandler) SendTestEmail(c *gin.Context) {
     <h2 style="color: #333;">` + req.Subject + `</h2>
     <div style="color: #666; line-height: 1.6;">` + req.Body + `</div>
     <hr style="border: none; border-top: 1px solid #eee; margin: 30px 0;">
-    <p style="color: #999; font-size: 12px;">This is a test email sent from MyCrib Admin Panel.</p>
+    <p style="color: #999; font-size: 12px;">This is a test email sent from Casera Admin Panel.</p>
 </body>
 </html>`