Guide every installer to a verified first SVG

[konojunya]

Summary

• Document Homebrew, Cargo, checksum/attestation-verified direct installation, and the pinned Aqua registry in all four locales.
• Keep init, check, render, format, upgrade, and uninstall guidance on one page, preserving the browser walkthrough.
• Execute the actual localized first-render commands against the published CLI in CI; reject missing or unsafe command drift.

Verification

• 19 tests, deterministic generation, immutable machine-resource validation, CLI release freshness
• Four isolated first-render walkthroughs against published Cargo CLI 0.5.1
• Locale heading/code/link contract validation

No runtime, release artifact, or engine behavior changes.