Add Toggle to Allow Overlapping Memberships

Summary:
Introduce an optional toggle within the membership setup that allows overlapping memberships. This will provide greater flexibility for managing unique member scenarios and support various business models more effectively.

Use Case Examples:

Paused Membership + One-Day Access:
Members may occasionally pause their primary membership (e.g., due to travel or injury) but still wish to purchase a one-day pass for an ad-hoc visit. Currently, overlapping memberships are not supported, making this scenario difficult to accommodate without manual workarounds.
Personal Trainer Rolling Memberships:
Personal trainers or coaches may run recurring (rolling monthly) membership plans. Allowing overlapping memberships would enable simultaneous management of these separate plans.

Proposed Functionality:

Add a toggle option in the membership setup interface labeled “Allow Overlapping Memberships.”
When enabled, this setting allows the system to accept and activate multiple memberships for a single member, regardless of existing active or paused plans.
Each membership should retain its own billing, validity, and usage rules.

Benefits:

Supports more nuanced and flexible membership models.
Reduces manual workarounds and the risk of data entry errors.
Enhances user experience by accommodating real-world member behaviours.