manatee: Add schema

The household weekly plan at schema.ppp.pm: its module, certificate,
DNS record, backup and secrets. The link to puppy-tracker is prepared
but commented out until puppy-tracker with the integration feed is
deployed.

flake.nix

@@ -99,6 +99,13 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
+    schema = {
+      # Switch to the gitea URL once the repo is pushed there:
+      # url = "git+ssh://gitea@git.ppp.pm:1122/alex/schema.git?ref=main";
+      url = "path:/home/alex/code/schema";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
     todo = {
       url = "git+ssh://gitea@git.ppp.pm:1122/alex/todo.git?ref=main";
       # url = "git+file:///home/alex/code/todo?ref=main";