fix(tui): replace alpha badges with version

[johntmyers]

Summary

Remove the obsolete ALPHA labels from the TUI splash screen and title bar. Keep the resolved OpenShell version visible in both locations and align local Git-derived versions with the canonical release-version algorithm.

Related Issue

No issue required: this is an obvious localized TUI labeling and development-version bug fix.

Changes

• Remove the ALPHA badge from the splash screen and title bar
• Display the resolved OpenShell version beside the title-bar brand
• Derive local versions from exact release tags or the latest merged stable tag, matching tasks/scripts/release.py
• Re-run version derivation when Git HEAD or tag metadata changes
• Add version parsing and title-bar rendering regression tests
• Update the TUI development skill examples

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (not applicable: no gateway or sandbox behavior changed)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable: no architecture boundaries changed)