[Phase 14] Cut and validate the first installable release

[cosentinode]

Scope

Cut the first real BitByGit release through the existing tagged-release workflow and validate that its published artifacts are usable on every supported platform. This closes the gap between release automation and the Phase 14 success condition.

Acceptance Criteria

• Select and document the initial semantic version, then create and push the corresponding signed or annotated release tag according to repository policy.
• The release workflow completes successfully and publishes versioned archives plus checksums for every supported target.
• The GitHub release contains release notes, all expected artifacts, and no unexpected or secret-bearing files.
• Published checksums are verified against downloaded artifacts.
• Installation and --version smoke checks pass from release artifacts on Linux, macOS, and Windows runners.
• Any defect discovered while cutting or validating the release is fixed through a linked pull request and independently reviewed before retrying.

Verification

• Inspect the tagged Release workflow run with gh run view.
• Inspect the release with gh release view and download artifacts with gh release download.
• Verify archive contents and checksums.
• Run the repository release/installation smoke tests for all supported targets.

Notes

Issues #57 and #61 implemented release packaging and publication automation, but PR #76 explicitly did not create a real tag or release. This issue must complete before the Phase 14 umbrella issue #16 closes.