fix(release): support product-prefixed tag recovery

[Proxicon]

Summary

• Support both canonical v... tags and the existing RatelDesk-... release-tag format.
• Add an exact-tag workflow_dispatch recovery path and use the selected tag consistently throughout the workflow.
• Keep one release-version gate in the workflow and document the recovery command; there is no separate release test helper to maintain.

Root cause

Issue #80 identified that the release workflow only listened for tags matching v*. The published RatelDesk-0.1.1-beta.3 tag therefore created a GitHub release without starting the release workflow, leaving it with no assets.

Safety

The existing protection against modifying a published, non-draft release remains unchanged. This PR fixes future tag pushes and provides a deliberate exact-tag dispatch path without weakening that guard.

Validation

• Direct valid and invalid tag checks against tools/release/validate-release-version.sh
• Shell syntax checks for the release validator
• YAML parse of .github/workflows/release.yml
• dotnet msbuild src/Helpdesk.API/Helpdesk.API.csproj -getProperty:Version
• git diff --check

Closes #80