Implement Import Validation for Bulk Grant Uploads

[Abd-Standard]

Description:
Improve bulk grant creation by validating uploaded data before records are added to the system.

Acceptance Criteria:

Invalid rows are identified.
Clear validation errors are provided.
Valid records can be imported safely.

[FaithUwaoma]

I have great experience to fix this issue for you.

[N-thnI]

Dear maintainer please assign me this issue

[Osuochasam]

Dear maintainer please assign me this issue

[grantfox-oss]

🦊 GrantFox — @Osuochasam has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #162)
2. Your PR will be reviewed by the Core-Foundry maintainers

Good luck! Track your progress on GrantFox.