[Wave 9] Remove private-key logging from copy-paste examples

[truthixify]

Problem

Several examples print private keys, secrets, or derived key material to the console. Even with test values, this teaches unsafe operational behavior.

Done when

• Replace secret output with redacted labels.
• Add warnings where a secret is intentionally constructed.
• Scan docs examples for secret-like identifiers and logging calls.
• Keep auditor-only fixtures isolated from user quickstarts.

[Chris-P-web]

@Chris-P-web has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

‎Hi Maintainer! I'd love to contribute to this issue. I can deliver a clean implementation while ensuring it's completed promptly and meets all requirements.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Chris-P-web to this issue.

[macsonfleek]

@macsonfleek has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer! Please assign me to this issue, I would love to work on it

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

[mxrtins04]

@mxrtins04 has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

🟢🟢🟢Hi maintainer, can i be assigned this issue pleasee?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mxrtins04 to this issue.

[drips-wave]

Congratulations, @Chris-P-web! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

🧑‍💻 @Chris-P-web: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊