Docs: Friday Cleanup: docs across 2 areas

[moxie-docs]

This PR covers 2 changes:

• Add docs for API behavior needs reader-facing documentation
• Add docs for Testing strategy is hard to infer from file inventory

This PR documents the API behavior and contract for the project information feature and outlines the current testing strategy and gaps, helping future maintainers understand frontend-backend interaction and where tests live. It centers on how the UI consumes the /api/project endpoint and the existing testing setup.

What these docs cover

• Frontend renders a Project Information UI by fetching GET ${config.backendUrl}/api/project and storing the JSON in projectData
• Expected API shape includes projectName, studentName, projectDescription, projectUrl
• Backend and frontend interactions rely on a single data contract with no explicit auth handling shown in App.js
• Frontend lacks error handling, retries, and validation for missing fields as described in the gotchas
• AGENTS.md guidance and testing documentation indicate frontend tests exist but backend tests are not configured
• Documentation notes potential need for frontend/backend tests and how to run them

How to review

• Verify the frontend App.js fetch path is GET ${config.backendUrl}/api/project and that it stores fields into projectData
• Check that the documented required API fields projectName, studentName, projectDescription, projectUrl are stated as the expected shape
• Confirm the doc notes lack of authentication handling in frontend/src/App.js and absence of error handling for fetch
• Ensure the gotchas mention endpoint availability and payload shape risks as described
• Verify the backend has no implemented tests and that the docs reflect the current testing setup referenced in AGENTS.md

Documentation updated

• moxie-docs/get-started/backend-readme.md
• moxie-docs/agents/agents.md

Referenced sources

• backend/README.md
• frontend/src/App.js
• AGENTS.md
• frontend/src/App.test.js
• backend/package.json