fix: derive CLI version from package metadata

[brendanjryan]

Summary

• Read the CLI version from package metadata instead of a hardcoded fallback
• Preserve TEMPO_WALLET_VERSION as the build-time override for packaged binaries

Motivation

Release bumps only update package.json, so a hardcoded source fallback can drift and break version checks after release PRs merge.

Key design considerations

• Keeps package.json as the single source of truth for source/dev execution
• Leaves the existing packaged-binary version override intact
• Fails explicitly if package.json is missing a version