Stacked bottom of #701. Replaces Makefile with justfile and hardens install.sh (strict mode, logging, HTTP probes, curl -f on model downloads, no v0.10.1-beta fallback).
Closes#700.
Configure actions/labeler@v5 to automatically label PRs based on file paths.
Maps changes to: app, web, documentation, ci, tests, installer, resources, dependencies.
Creates 6 new labels to complement existing issue labels for better PR organization.