Add bulk waitlist invitation operations

[yacosta738]

Context

Back Office waitlist administration should support controlled batch invitation of eligible entries so onboarding does not require one-by-one manual work.

Goal

Implement bulk invitation over eligible waitlist entries with per-entry success and failure reporting.

Scope

• Bulk-select eligible waitlist entries at the application/API level.
• Create invitations for eligible entries.
• Report per-entry success and failure outcomes.
• Preserve auditability and safety for batch operations.

Out of Scope

• Complex campaign segmentation.
• Waitlist scoring.
• Generic bulk mutation framework.

Domain Rules

• Only eligible entries should receive invitations.
• Duplicate active invitation rules still apply per entry.
• Bulk execution must not hide partial failures.

API Contract

• Expose an explicit bulk invitation command or equivalent safe batch endpoint.
• Response should distinguish successful and failed entries.

Security

• Requires explicit administrative authorization.
• Batch operations must respect the same invariants as single-entry invite flows.

Audit

• Bulk invitation activity must remain auditable, whether as individual events, batch metadata, or both.

Observability

• Track batch size, success count, and failure count.

Acceptance Criteria

1. Administrators can bulk invite eligible waitlist entries.
2. Ineligible or duplicate cases do not prevent reporting of other results.
3. The operation reports success and failure per entry.
4. Auditability is preserved for the resulting mutations.

Gherkin

Feature: Bulk invite waitlist entries

  Scenario: Bulk invite eligible waitlist entries
    Given eligible waiting entries are selected
    When an administrator performs bulk invitation
    Then invitations should be created for eligible entries
    And the result should report success and failure per entry

Testing

• Application
• API
• Integration

Dependencies

• Add Back Office waitlist queries, filtering, and search #667
• Convert waitlist entries into invitations and track conversion state #666

References

• RFC sections 19, 20, 34, 45

[linear-code]

DALLAY-569