Document Cargo installation and CLI 0.5.1

[konojunya]

Summary

• Pin the published CLI 0.5.1 release and its exact source commit.
• Explain the official stack-diagram-cli Cargo package, prerequisites, installer-owned upgrades, and shell integration in all four locales.
• Regenerate the shared skill and Web documentation from the canonical sources.
• Preserve every immutable machine v1.0.0 resource byte.

Validation

• Deterministic generation and drift check; 17 tests
• Four generated skill commands exercised against the published Cargo CLI 0.5.1
• Live release version and tag/source verification
• Immutable machine resources unchanged