[SCF high][easy] Redact RPC credentials from readiness output

[karagozemin]

Goal\nPrevent embedded RPC credentials from appearing in public readiness diagnostics.\n\n## Acceptance criteria\n- Sanitize user info and sensitive query parameters.\n- Preserve safe host and network diagnostics.\n- Add secret-bearing URL regression tests.\n\n## Complexity\nHigh - small implementation, high reliability value.

[The-Big-Danny]

@The-Big-Danny has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

hello, can i WORK on this issue?, i can fix it.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @The-Big-Danny to this issue.

[Joseph-tech10]

@Joseph-tech10 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer, I have reviewed this work and I will like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Joseph-tech10 to this issue.

[emirykl]

@emirykl has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hey, I want to take that issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @emirykl to this issue.

[drips-wave]

Congratulations, @emirykl! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @emirykl: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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