phase 0: nix flake devshell + process-compose orchestrator.
mirrors youngstartup setup. flake provides php 8.4, composer, nodejs, postgresql, cypress, typescript, process-compose. shellHook seeds a per-repo postgres cluster at .postgres/. process-compose orchestrates postgres + backend (laravel) + vite (vue spa) for local dev. .envrc auto-loads the flake via direnv. mailpit and gitlab-ci-local omitted - not needed for tide blogging app.