fix(release): qualify manually pushed prerelease tags #4334

User Story

As an OpenShell release maintainer, I need to create a prerelease tag from the command line and have it enter qualification automatically, then choose the latest qualified candidate for stable publication.

Description

Restore Release Tag's push trigger for prerelease tags and add a short internal release skill describing candidate selection, maintainer approval, and tagging the qualified commit as stable. When no prerelease exists for the intended version, create and qualify one first.

Context

Release Tag currently excludes -pre.* from its push trigger. Release Auto-Tag works around that by explicitly dispatching the workflow, but manually pushed prerelease tags do not start qualification. Keep Auto-Tag's dispatch because pushes made with GITHUB_TOKEN do not trigger another workflow.

Definition of Done

• A manually pushed vX.Y.Z-pre.N tag starts Release Tag qualification.
• Release Auto-Tag retains its explicit dispatch.
• A concise internal skill explains selecting the latest qualified prerelease and tagging that exact commit as stable after maintainer approval.
• Contributor skill discovery and CI documentation describe the resulting workflow.