Harden release post-publication workflows

[masarray]

Goal

Prevent the non-binary post-publication failures observed after the successful ARSAS v1.6.20 release.

Fixes

• write the GitHub Contents API request through an explicit UTF-8 no-BOM temporary JSON file instead of piping PowerShell text to gh api --input -
• retry release metadata and checksum-asset discovery before synchronizing public evidence, removing the race where documentation starts before GitHub Release visibility
• stop the legacy artifact-publication workflow from running whenever only landing/release-notes.json changes; it now runs only when its explicit verified-publication request or workflow changes

No application binary, tag, checksum or published v1.6.20 asset is changed by this PR.

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