InstallerV2: minimal phases/components + CI smoke tests

[philipnickel]

This PR continues the new macOS installer (V2) with a simpler architecture.

Key changes:

• Add minimal pre/post phases and Python/VSCode/packages components
• Provide local entrypoint and universal dist build script
• Fix core run flow to be set -e safe
• CI workflow (macOS) builds dist and runs CLI/GUI dry-run smoke tests, and repo entry script

Notes:

• Telemetry is disabled in CI; GUI test runs in dry-run mode
• Future: integrate analytics events and richer post-verify report