[Phase 5] Sync Problems Page — List and Retry Failed Syncs

[ViRUS-0-0]

Description:

When a sync fails or gets stuck, there's currently nowhere for an organiser to see it. This issue adds a dedicated page under the HubSpot section that lists every order that hasn't synced successfully, with the reason why and actions to fix it.

Tasks:

• Add a "Sync problems" page linked from the HubSpot settings page
• The page lists all sync records for that event with status pending or failed, showing: order code, status (pending / failed), when it last attempted, and the error message in plain language
• Add a filter to switch between showing pending only, failed only, or all problem records
• Add a "Retry" button on each row — clicking it re-queues just that one order and sets its status back to pending
• Add a "Retry all failed" button at the top that re-queues every failed record at once
• Add a "Dismiss" button on each row — clicking it marks the record as dismissed so it no longer appears in the problems list, without deleting the history
• If there are no problem records, show a clean "Everything is synced" message instead of an empty table
• The page is only visible to organisers with access to that event
• Write tests checking: retry re-queues the task, dismiss removes it from the list, "retry all" re-queues every failed record, records from other events never appear

Acceptance Criteria:

• Organisers can see all stuck or failed syncs in one list
• Retrying a single record re-queues it and updates its status
• Retrying all failed records works in bulk
• Dismissing a record removes it from the problems list
• When everything is synced the page says so clearly