Retry transient release package installs and verify them independently

[highbyte]

A transient Broken pipe during Linux Homebrew installation required a manual release-job retry even though the published archive was valid. Add a shared installation helper for Homebrew and Scoop that retries recognized transient failures at most three times, with 10- and 30-second delays, and retains each attempt's output and exit code.

The helper checks installation state before retrying. A completed install must match the exact release version and source commit; partial installs, integrity or permission failures, unknown errors, and version mismatches stop. Functional smoke tests and cleanup remain mandatory. Retries cover Wrighty installation only, not package-manager bootstrap, publication, uploads, or repository pushes.

Add the verify-installation operation to the existing Release workflow so changes can be tested from a branch against an already published immutable release. It reuses the release installation jobs, uses read-only repository access, and skips release credentials, publication, and package-manifest updates. Document the operation and add cross-platform failure-handling checks to CI.

Validation:

• Installation-only GitHub Actions run passed against v0.19.0-alpha on Linux/Homebrew, macOS/Homebrew, and Windows/Scoop, including exact version/commit verification, Local Markdown lifecycle and stored-state checks, and uninstall cleanup.
• Controlled failure/retry tests passed on all three runners, including the native Windows Scoop command bridge. Real installs succeeded on their first attempt; simulated failures exercise retry behavior.
• 19 local tests passed, with the Windows-only test deferred to the successful hosted run. Workflow validation with actionlint and git diff --check passed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud