feat: prometheus nixos module & test-container

for testing grafana in container
export QEMU_NET_OPTS="hostfwd=tcp::3000-:3000"
 nixos-rebuild build-vm --flake .#test-container
and then run the container, login is test/test

and the grafana port is forwarded to host machine, yay

.gitignore

@@ -4,3 +4,4 @@
 /result
 /routes/static/out.css
 /nixos.qcow2
+/data/