fix(events): show customer phone in event details view (#331)

The phone field added in #322 was wired into the edit form but never
rendered in the read-only event-info panel, so admins could only see the
number while editing. Add a phone row gated on event_phone_field_enabled
(same toggle the form uses), and tighten the Event type so customer_phone
is no longer accessed via `(event as any)`.

frontend/src/types/index.ts

@@ -7,6 +7,7 @@ export interface Event {
   event_date: string | null;
   customer_name?: string;
   customer_email: string;
+  customer_phone?: string | null;
   admin_email: string;
   welcome_message?: string;
   color_theme?: string;