feat: group same booking reports together

[Udit-takkar]

What does this PR do?

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• 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.
• I confirm automated tests are in place that prove my fix is effective or that my feature works.

How should this be tested?

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Summary by cubic

Grouped booking reports by booker email and enabled actions to block or dismiss all reports in a group. Updated UI, APIs, and repository to support grouped listing and multi-report actions.

• New Features

  • Added grouped listing via findGroupedReportedBookings with one row per email and a count badge.
  • Details modal now shows “Related bookings” with links to each report’s booking.
  • Add-to-blocklist and dismiss actions now accept multiple report IDs and apply to the whole group.
  • Watchlist operations de-duplicate by normalized email/domain, create one entry, and link all related reports.

• Migration

  • TRPC dismiss endpoints now expect reportIds: string[] instead of reportId. Update callers to pass arrays.

^{Written for commit ad64fff. Summary will update on new commits.}