[Task] Replace placeholder text with graceful error state in EditFieldDrawer for unregistered field types #9539

Background

When a BasicField enum value has no corresponding case in the MemoFieldDrawerContent method switch statement, the drawer silently falls through to the default branch and renders raw dev placeholder text (TODO: Insert field options here) visible to any admin user.

Goal

The edit drawer never shows raw placeholder text to users — unhandled field types either render the correct Edit component or fail with a clear, user-facing error state.

Acceptance Criteria

• The default branch in MemoFieldDrawerContent method no longer renders <div>TODO: Insert field options here</div>
• Unhandled field types display a meaningful error state (inline message or toast) instead of placeholder text
• A TypeScript exhaustive check (const _exhaustiveCheck: never = field.fieldType) is added so missing case entries are caught at compile time
• tsc --noEmit fails when a new BasicField value is added without a corresponding case
• Tests added covering the unregistered field type error path

Notes

Affected file: apps/frontend/src/features/admin-form/create/builder-and-design/BuilderAndDesignDrawer/EditFieldDrawer/EditFieldDrawer.tsx