feat: Implement booking audit producer-consumer pattern with feature flag support

[hariombalhara]

What does this PR do?

• Fixes #XXXX (GitHub issue number)
• Fixes CAL-XXXX (Linear issue number - should be visible at the bottom of the GitHub issue description)

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• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. If N/A, write N/A here and check the checkbox.
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• I haven't read the contributing guide
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---

Summary by cubic

Adds an async producer–consumer pipeline for booking audit events behind a feature flag. This decouples audit recording from booking flows and processes audits in the background with schema validation and migration.

• New Features
  • BookingAuditProducerService interface with a Tasker-based implementation.
  • BookingAuditTaskConsumer validates payloads, checks org feature flag, migrates schemas, and routes actions.
  • Tasker: new bookingAudit task, passes taskId to handlers, and Task.updatePayload for migrations.
  • DI modules/containers and tokens for producer and consumer.
  • BookingEventHandlerService queues audit tasks for created/rescheduled and other booking events.
  • Discriminated unions for BookingAuditTaskPayload and BookingAuditActionData.

^{Written for commit fde380a. Summary will update automatically on new commits.}

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Project	Deployment	Preview	Comments	Updated (UTC)
cal-companion	Error			Nov 30, 2025 9:17am

2 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
cal	Ignored			Nov 30, 2025 9:17am
cal-eu	Ignored			Nov 30, 2025 9:17am

[hariombalhara]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add plan for more actions #25162
• feat: [Booking Audit Stack - 6] Integration of Booking Audit System #25120
• feat: add linkedBookingUid to booking audit for reschedule tracking #25202
• feat: Add booking audit log viewer with filtering and permissions #25152
• feat: Implement booking audit producer-consumer pattern with feature flag support #25470 👈 (View in Graphite)
• feat: [Booking Audit Stack - 3] Integrate Booking Audit Action services  #25125 : 1 other dependent PR (#24902 )
• feat: Add support to audit and view audit log with Booking CREATED action #25468
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.