replace NPM with vanilla nginx + certbot

- nginx:alpine replaces nginx-proxy-manager
- certbot on host with standalone issuance and auto-renewal
- per-site nginx configs in conf.d/ (HTTP->HTTPS, bare->www)
- container names use underscores (timothykim_net)
- setup.sh: automated cert issuance, dynamic app startup
- deploy.sh: nginx -t guard, graceful image-not-found
- new-app.sh: Gitea API repo creation, nginx conf generation
- add ARCHITECTURE.md, USECASES.md, CLAUDE.md
- remove old NPM data/certs from tracking

.gitignore

@@ -1,3 +1,5 @@
 containerd/
 vultr/
-docker/nginx/data/logs/
+docker/nginx/data/
+docker/nginx/certs/
+docker/nginx/certbot/