feat(applications): add search and date filters

[PHADAR6]

Overview

This PR adds optional search and date-range filters to the admin GET /ngo-applications endpoint. Reviewers working through a backlog can now search by applicant name or email and narrow results by submission date, combined with the existing status filter.

Related Issue

Changes

🔍 Application List Filters

• [MODIFY] src/routes/ngoApplications.ts

  • Added optional search query param that matches against applicant name / email.
  • Added optional submittedAfter and submittedBefore query params to bound results by submission date.
  • Filters compose with the existing status filter rather than replacing it.

• [MODIFY] test/routes/ngoApplications.test.ts

  • Added tests covering search, submittedAfter / submittedBefore, and combinations with the existing status filter.

Verification Results

npm run lint
npm run typecheck
npm test

Acceptance Criteria	Status
Add optional search (name/email) and submittedAfter/submittedBefore params to the admin list	✅ Implemented in src/routes/ngoApplications.ts
Combine with the existing status filter and add tests	✅ Filters compose with status; covered in test/routes/ngoApplications.test.ts

Closes #129

[Ashborne267]

@PHADAR6 please resolve conflict