Infra now always runs unit tests + vet on PRs, and additionally runs
`pulumi preview --diff` (posted as a PR comment) when the infra, gui, or
api code changes — since any of those can change what gets deployed.
Each sub-project (gui, api, infra) now owns its own Makefile, and the
root Makefile is a lean delegator for the base commands (run, build,
test, clean, fmt). Odin source, deps, and web assets live under gui/
(gui/src, gui/lib, gui/www), with scripts kept under gui/scripts for
build tooling only.
sam_oneal