feat: implement flash messages system with auto-dismiss notifications

- Add flash message helper and styles for consistent notifications
- Replace Devise error messages with flash-based notifications
- Add dashboard page with event statistics
- Configure SMTP settings for development and production
- Update authentication controllers to use flash messages
- Add JavaScript controller for auto-dismiss functionality

app/assets/stylesheets/components/flash.css

@@ -0,0 +1,39 @@
+/* Flash Messages - Theme Integration */
+.flash-message {
+  @apply max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 mb-4;
+}
+
+/* Base styles for all flash messages */
+.flash-message .flex {
+  @apply rounded-md p-4 border shadow-md;
+}
+
+/* Success message styles */
+.flash-message-success {
+  @apply bg-green-50 border-green-100 text-green-800;
+}
+
+/* Error message styles */
+.flash-message-error {
+  @apply bg-red-50 border-red-100 text-red-800;
+}
+
+/* Warning message styles */
+.flash-message-warning {
+  @apply bg-yellow-50 border-yellow-100 text-yellow-800;
+}
+
+/* Info message styles */
+.flash-message-info {
+  @apply bg-blue-50 border-blue-100 text-blue-800;
+}
+
+/* Notice message styles */
+.flash-message-notice {
+  @apply bg-purple-50 border-purple-100 text-purple-800;
+}
+
+/* Alert message styles */
+.flash-message-alert {
+  @apply bg-red-50 border-red-100 text-red-800;
+}