feat(backend): add routes-f get-by-id endpoint #297

[CMI-James]

Description

Closes #297

Changes proposed

What were you told to do?

Backend: Add routes-f get-by-id endpoint #297

What did you do?

• Created a new API route app/api/routes-f/items/[id]/route.ts to handle fetching a single Routes-F item.
• Implemented robust ID validation:
  • Returns 404 if the ID is missing.
  • Returns 400 if the ID format is invalid (non-numeric).
• Added mock data for Routes-F items to simulate a database response.
• Included an ETag header in the response for efficient browser/CDN caching.
• Created comprehensive unit tests in app/api/routes-f/items/[id]/tests/route.test.ts to cover happy paths (200 OK) and error paths (400 Bad Request, 404 Not Found).

Check List (Check all the applicable boxes)

🚨Please review the contribution guideline for this repository.

• My code follows the code style of this project.
• This PR does not contain plagiarized content.
• The title and description of the PR is clear and explains the approach.
• I am making a pull request against the main branch (left side).
• My commit messages styles matches our requested structure.
• My code additions will fail neither code linting checks nor unit test.
• I am only making changes to files I was requested to.

Screenshots/Videos

N/A (Backend API implementation verified via unit tests).

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[davedumto]

hey @CMI-James fix failing ci

[davedumto]

hi @CMI-James ci is failing