feat(grfn/bbbg): Init

This will eventually become a signup sheet + no-show tracker for my
local board game meetup group

Change-Id: Id8d1d80d95d1e2fda5041275cff2fecfd6fa43f1

users/grfn/bbbg/arion-compose.nix

@@ -0,0 +1,15 @@
+{ ... }:
+
+{
+  services = {
+    postgres.service = {
+      image = "postgres:12";
+      environment = {
+        POSTGRES_DB = "bbbg";
+        POSTGRES_USER = "bbbg";
+        POSTGRES_PASSWORD = "password";
+      };
+      ports = [ "5432:5432" ];
+    };
+  };
+}