Comment section on reimbursement requests only allows single image upload

### Describe your goals

Expected Behavior:

The comment section should support multiple image/file uploads, consistent with how the receipt section works.
Why it matters:

Sometimes a single comment needs supporting context across multiple images (e.g. multiple receipt pages, before/after photos, itemized breakdowns). Limiting to one image per comment forces users to either split context across multiple comments or leave information out entirely.
Suggested Fix:

Allow multi-file selection on the comment attachment input, similar to how the receipt section already handles it.

### Describe the bug

When submitting a reimbursement request, the receipt section correctly supports uploading multiple files. However, the comment section on the same reimbursement only allows attaching a single image there's no way to attach more than one. instead of making new comment.

Start by locating the reimbursement request comment attachment input and compare it with the receipt section's existing multi-file upload behavior. Update the comment attachment flow so one comment accepts multiple images or files, then verify that several attachments can be selected and submitted together without requiring separate comments.

Written by the indexing model from the issue text.