feat: soft delete

[PatrikKozak]

What?

This PR introduces foundational backend support for soft delete functionality via a new softDeletes root-level property on collections. When enabled, collections support soft deletion by including a deletedAt timestamp on documents.

import type { CollectionConfig } from 'payload'

const Posts: CollectionConfig = {
  slug: 'posts',
  softDeletes: true, // <-- Newly add collection config prop @default false
  fields: [
    {
      name: 'title',
      type: 'text',
    },
    // other fields...
  ],
}

How?

• New softDeletes config prop on collections.
• Conditional injection of deletedAt field if softDeletes is enabled.
• Extended support for trash query param across LOCAL, REST and GRAPHQL API operations:
  • find
  • findByID
  • findVersions
  • findVersionByID
  • update
  • updateByID
  • delete
  • deleteByID
• Appended delete access control in update & updateByID operations to prevent soft deleting if restricted by delete access in the collection config.

Notes

• This PR only introduces backend support and does not modify admin UI behavior. A separate frontend PR will expose the actual soft delete UI and interaction.

• Fully covered by tests validating the behavior of all trash query params on soft-deletable collections.