Show rate not valid error after deleting per diem rate

[MelvinBot]

Explanation of Change

When a per diem rate is deleted from a workspace, two issues occur:

1. The "Rate not valid for this workspace" error banner does not appear when viewing the expense
2. Duplicating the expense shows an "unexpected error" instead of a proper message

Root cause: Unlike deletePolicyDistanceRates which optimistically adds CUSTOM_UNIT_OUT_OF_POLICY violations to affected transactions when a distance rate is deleted, deleteWorkspacePerDiemRates only updates the policy custom unit and never touches transaction violations. Additionally, MoneyRequestView.tsx has a fallback check (isDistanceRequest && !rate) for distance requests but no equivalent for per diem requests.

This PR makes two fixes:

1. Primary fix (PerDiem.ts): Updates deleteWorkspacePerDiemRates to accept transactionIDsAffected and transactionViolations parameters and optimistically add CUSTOM_UNIT_OUT_OF_POLICY violations to affected transactions — mirroring the existing pattern in deletePolicyDistanceRates. The workspace per diem pages (WorkspacePerDiemPage.tsx and WorkspacePerDiemDetailsPage.tsx) are updated with transaction/violation selectors to find and pass affected transactions, following the same pattern as the distance rate pages.

2. Secondary fix (MoneyRequestView.tsx): Adds a per diem fallback to the isCustomUnitOutOfPolicy check that directly validates the rate still exists in the policy via getPerDiemRateCustomUnitRate, similar to the existing distance request fallback. This provides a safety net even if the violation is missing for any reason.

Fixed Issues

$ #82584
PROPOSAL: #82584 (comment)

Tests

1. Have a workspace with per diem rates imported
2. Create a per diem expense (e.g., Afghanistan, qty 6, breakfast)
3. Delete the rate used in step 2 from the workspace per diem settings
4. Go to the workspace chat and open the expense
5. Verify the "Rate not valid for this workspace" error banner is shown
6. Tap more → duplicate expense
7. Verify duplication is blocked (the hasCustomUnitOutOfPolicyViolation guard prevents it)

• Verify that no errors appear in the JS console

Offline tests

1. While offline, delete a per diem rate from workspace settings
2. Verify the violation is optimistically added (error banner shows immediately)
3. Reconnect to the network
4. Verify the violation persists after sync

QA Steps

1. Have a workspace with per diem rates imported
2. Create a per diem expense using one of the rates
3. Delete the rate used in step 2 from workspace per diem settings
4. Open the expense
5. Verify the "Rate not valid for this workspace" error is displayed
6. Try to duplicate the expense
7. Verify duplication is blocked with an appropriate error, not an "unexpected error"

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
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Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

[codecov]

Codecov Report

✅ Changes either increased or maintained existing code coverage, great job!

Files with missing lines	Coverage Δ
...c/components/ReportActionItem/MoneyRequestView.tsx	67.06% <100.00%> (+0.31%)	⬆️
src/libs/actions/Policy/PerDiem.ts	0.00% <0.00%> (ø)
.../workspace/perDiem/WorkspacePerDiemDetailsPage.tsx	0.00% <0.00%> (ø)
...c/pages/workspace/perDiem/WorkspacePerDiemPage.tsx	0.00% <0.00%> (ø)
... and 10 files with indirect coverage changes

[yifan19860831-hub]

Hi! I'd like to work on this issue. Can I get assigned? 🙏

[situchan]

@MelvinBot pull main and fix conflict

[MelvinBot]

Merged main and resolved the conflict in src/pages/workspace/perDiem/WorkspacePerDiemPage.tsx — it was a simple import conflict between useTransactionViolation (from this PR) and useWorkspaceDocumentTitle (from main). Both imports are kept.