Add release automation scripts

[virtualian]

Context

Created during issue #83 (workflow/versioning standards restructure).

Problem

The new standards define a manual release process, but release automation would reduce errors and enforce consistency.

Proposed Solution

Add release automation that:

• Validates preconditions (on main, clean working directory, tests pass)
• Bumps version according to semver (patch/minor/major)
• Creates annotated git tag with consistent naming (vX.Y.Z)
• Pushes tag to remote

Alternatives Considered

Manual process is documented in prj-version-control-standard.md and works, but is error-prone.

Additional Context

See prj-version-control-standard.md Release & Tagging section for the manual process this would automate.