[Perf] Compute transaction violations once in MoneyRequestReportPreviewProvider and share via context

[cristipaval]

Problem

The report preview action buttons need transaction violations to decide what to show.
Right now this is computed more than once instead of one shared place. Computing
violations is not free, so doing it per-button adds extra work on each re-render.

Goal

• Compute the transaction violations one time in MoneyRequestReportPreviewProvider.
• Share the result through a context slice.
• Update the action buttons to read violations from context instead of computing
  them on their own.
• Measure the performance gain first, and add the numbers to the PR so we can
  confirm the change is worth it.

Related

• Parent: [Due for payment 2026-07-14][$250] Perf/decompose money request report preview #94603
• Provider introduced in: [NOQA] perf: add MoneyRequestReportPreview layout components #94681
• Related refactor: [Perf] Refactor ReportPreviewActionButton to consume MoneyRequestReportPreviewProvider #95366

Issue Owner

Current Issue Owner: @linhvovan29546

[OlimpiaZurek]

Update:

• prepared a draft PR: Perf/report preview provider violations slice #96053 for this. It's a stacked PR for now (from this one) and will need to be rebased once this one is merged. Then I'll move it to review.