User Story
As a system operator, I want payment orders to be soft deleted instead of permanently removed, to maintain data integrity and audit history while still allowing cleanup of old records.

Acceptance Criteria

1. GIVEN a payment order is deleted
   WHEN using normal deletion
   THEN the record is soft deleted by setting deleted_at

2. GIVEN querying payment orders
   WHEN no special context is provided
   THEN only non-deleted records are returned

3. GIVEN querying payment orders
   WHEN using SkipSoftDelete context
   THEN all records including soft-deleted ones are returned

4. GIVEN a sender profile is deleted
   WHEN the cascade delete triggers
   THEN associated payment orders are soft deleted

Tech Details

• Create new SoftDeleteMixin in schema/mixins.go following Ent documentation for soft delete
• Add SoftDeleteMixin to both LockPaymentOrder and PaymentOrder schemas
• Update PaymentOrder edge in SenderProfile to use entsql.Cascade
• Add SkipSoftDelete context utility function
• Create database migration for new deleted_at field
• Add soft delete functionality to LockPaymentOrder and PaymentOrder schemas
• Ignore writing tests for this ticket

Notes/Assumptions

• Both schemas currently use TimeMixin
• Multiple mixins can be combined
• Existing deletion logic will be replaced by soft delete
• Permanent deletion still possible with SkipSoftDelete context

Open Questions