fix(api): return 204 when analysis has no request details

[vvatelot]

Summary

• GET /{version}/ecoindexes/{id}/requests now returns 204 No Content when the analysis exists but no request details were collected.
• A missing analysis still returns 404. Successful lookups with stored requests still return 200 and the JSON payload.
• OpenAPI spec and unit tests are updated accordingly.

Test plan

• Call GET /v1/ecoindexes/{id}/requests with an unknown id → 404
• Call it with an existing analysis that has no stored requests → 204, empty body
• Call it with an existing analysis that has request details → 200 + RequestsDetailResponse
• Confirm Swagger/OpenAPI documents the 204 response

Made with Cursor

[github-actions]

Branch coverage •

File	Stmts	Miss	Cover	Missing
bases/ecoindex/backend/routers
ecoindex.py	48	13	73%	76, 89, 97, 99, 120, 124–125, 129, 197–198, 203–204, 210
TOTAL	1757	538	69%