fix(acl_list_prompts): implement ACL for list prompts

[galagaevdc]

Summary

Fix ACL for list of prompts

Pre-Agreement Checklist (required)

Please check all boxes before requesting review:

• I have read and followed the contribution guidelines.
• This PR addresses an existing issue or a concluded discussion.
• If there was no existing issue/discussion, I opened one first to align with maintainers before submitting this PR.
• I confirmed the issue/discussion priority with maintainers and understand low-priority items may receive limited attention.
• I kept this PR focused and reasonably small; if the work is large, I split it into smaller PRs where possible.
• Any AI-generated code in this PR was reviewed by a human author.

Validation Checklist

• go test ./... passes locally.
• scripts/test-mcpjungle.sh passes locally.
• I added or updated tests for new behavior where applicable.
• I updated documentation for user-facing changes where applicable.

Linked Context

• Issue(s): ACL: Unauthorized clients can still see all prompts & resources available in mcpjungle #220
• Discussion(s):