Copy odometer data during transaction merge

[MelvinBot]

Explanation of Change

When merging two odometer distance expenses, the odometer readings (odometerStart, odometerEnd) and their images (odometerStartImage, odometerEndImage) were not being transferred from the selected transaction to the merged result. This caused the merged expense to display stale odometer data from the target transaction instead of the user's chosen values.

The fix propagates odometer data through the entire merge pipeline:

1. MergeTransaction type — Added odometerStart, odometerEnd, odometerStartImage, odometerEndImage fields so the merge flow has storage for these values.
2. getMergeFieldUpdatedValues — When the merchant field is selected for an odometer distance request, copies the odometer readings and images from the selected transaction's comment.
3. buildMergedTransactionData — Overrides the target transaction's odometer values in the comment with the merge transaction's values (when present).
4. API params (mergeTransactionRequest) — Includes odometer data in the comment JSON sent to the backend.
5. Optimistic data (getOnyxTargetTransactionData) — Includes odometer data in the optimistic Onyx update for immediate UI feedback.

Fixed Issues

$ #82658

Tests

1. Log in with an Expensifail account
2. Go to a workspace chat
3. Create two odometer expenses with different start/end readings
4. Open the expense report
5. Open any expense, click More > Merge
6. Select the other odometer expense > Continue
7. Select the second merchant > Continue
8. Click Merge expenses
9. Click Distance
10. Verify the odometer data updates to the value of the selected (merged) expense, not the old target values

• Verify that no errors appear in the JS console

Offline tests

1. Go offline before step 8 above (clicking "Merge expenses")
2. Verify the merged expense optimistically shows the correct odometer readings from the selected transaction
3. Go back online and verify the data persists correctly

QA Steps

1. Log in with an Expensifail account on staging
2. Go to a workspace chat
3. Create two odometer expenses with different distances (e.g., start: 1000, end: 1050 for one; start: 2000, end: 2100 for the other)
4. Open the expense report
5. Open any expense, click More > Merge
6. Select the other odometer expense > Continue
7. Select the second merchant > Continue
8. Click Merge expenses
9. Click Distance
10. Verify the odometer data matches the selected expense's values

• 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
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  • 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

[MelvinBot]

Fixed the failing ESLint check: FileObject was imported from a non-existent module @libs/FileUtils in src/types/onyx/MergeTransaction.ts. Changed the import to @src/types/utils/Attachment where the type is actually defined. This was the root cause of all 10 ESLint errors — the invalid import made FileObject resolve as an error type (any), which cascaded into no-redundant-type-constituents and no-unsafe-assignment errors in MergeTransactionUtils.ts and MergeTransaction.ts.

[MelvinBot]

The failing checks have been fixed. The previous TypeScript error (Cannot find module '@libs/FileUtils') was caused by an incorrect import path in MergeTransaction.ts. The fix commit corrected the import to @src/types/utils/Attachment. Both the TypeScript and ESLint checks are now passing.

[codecov]

Codecov Report

❌ Looks like you've decreased code coverage for some files. Please write tests to increase, or at least maintain, the existing level of code coverage. See our documentation here for how to interpret this table.

Files with missing lines	Coverage Δ
src/libs/MergeTransactionUtils.ts	76.31% <55.55%> (-0.86%)	⬇️
src/libs/actions/MergeTransaction.ts	58.08% <50.00%> (-0.41%)	⬇️
... and 12 files with indirect coverage changes