Add cloudpin

[paureis]

Summary

Adds a card for cloudpin, a guard that blocks cloud CLI commands (from a person or an AI agent) that would run on a different account than the one pinned for the repo.

• Tool Name: cloudpin
• Binary: cloudpin
• Primary Category: security
• Homepage / Repo: https://github.com/paureis/cloudpin

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Contribution Rules & Checklist

• No manual README edits: only data/tools/cloudpin.yaml is added.
• Exact file naming: data/tools/cloudpin.yaml, name: cloudpin.
• Allowed effects: read_files, write_files, environment_mutation, execute_code, network_access, remote_read.
• Guardrails: risk level is medium; two guardrails included anyway.
• Local validation passed:

  python scripts/lint_registry.py
  python scripts/generate_readme.py

I'm the author of cloudpin. Happy to adjust the risk level or effects if you read them differently.