Prepare README for first public release

[chezzof]

Summary

• Replace the pre-release README badge/text with release-ready GitHub Releases wording.
• Update launch/readiness docs so they no longer say the first public release must remain unpublished.
• Clarify that historical release-candidate checksums are not the final published download verification source.

What Changed

• README release badge now points at the latest semver GitHub Release badge.
• README release section now directs users to GitHub Releases for published artifacts and the release gate for local rebuilds.
• Release checklist/readiness docs now describe the first public release state without stale release-not published wording.
• Release notes template says "first public release" instead of "release candidate".

What Did Not Change

• No runtime code, UI implementation, backend behavior, dependencies, Electron security boundary, config schema, or tuning behavior changed.
• No release artifacts are committed.
• No GitHub Release is published by this PR.

Verification

• powershell -ExecutionPolicy Bypass -File scripts\release-check.ps1 -SkipPackage passed.
• git diff --check passed.
• Stale pre-release marker search for release-not published, not%20published, No public GitHub release, and first public release candidate returned no matches in README/docs.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Make release copy conditional until artifacts are uploaded

When this lands before the manual GitHub Release step, the README tells users that Windows artifacts are already attached to Releases and points them at rebuilding “the same release package”. The release docs still treat uploading SHA256SUMS.txt and public artifacts as a later manual gate, so in that state the badge/link can lead to no downloadable artifacts while the README no longer explains that users must build locally. Keep this wording conditional, or retain the no-public-release caveat, until the actual release assets are uploaded.

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