feat(raycast): add compare reports command and fixture-backed docs contracts

[JSONbored]

Summary

• add a top-level Raycast compare-reports command for the latest saved Nightward reports
• add fixture-backed docs checks that run documented commands against a committed home and verify output claims
• add Homebrew formula generation from signed release artifacts and wire it into release verification

What changed

• promoted report-history compare into its own Raycast entrypoint with read-only error handling and test coverage
• added a docs fixture home plus contract tests for stable fenced snippets, JSON shape claims, and stale future-as-shipped copy
• generated a tap-ready Homebrew formula from checksums.txt and verified both nightward and nw install paths
• updated install, distribution, release, and Raycast docs to match the current implementation truth

Why

• report comparison was buried in the dashboard and needed a first-class, read-only surface
• public docs had drifted away from real CLI behavior and needed executable contracts instead of static prose alone
• Homebrew support should stay tied to the signed release artifact shape instead of becoming a separate packaging path

Validation

• make ci-scripts-test
• make docs-qa
• make site-verify
• cargo fmt --all --check
• cargo test --workspace
• Raycast npm test, npm run lint, npm run build, npm run store-check, and npm audit --audit-level=moderate
• make gitleaks

Notes

• the Homebrew work is formula-generation scaffolding only; there is still no published public tap command
• the docs contract check stays read-only and fixture-backed, with no live or writeful behavior