fix(openapi): fix recorded session GET response

[luizhf42]

What

Fix the session recording GET response type.

Why

The spec previously typed this as a whole schema, but that endpoint only returns the session contents in NDJSON, recorded via Asciinema.

Closes shellhub-io/team#237

[github-actions]

Claude finished @luizhf42's task in 46s —— View job

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Code Review Complete

Reviewed 2 files across code quality, security, testing, language patterns, and architecture — no new issues found. The code looks good as-is.

I verified against the actual handler in cloud/internal/cloud/routes/session.go (GetSessionAnsciinema), which serves the recorded session file directly via c.FileFS(...) rather than returning a structured JSON object — so switching the 200 response from application/json + recordedSessionResponse to text/plain + type: string correctly reflects the real behavior. I also confirmed the deleted recordedSessionResponse.yaml schema has no remaining $ref references anywhere in openapi/.

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