services: gitea: add state to backup

Because I think `restic` will not deal with the compressed format of
`gitea`'s native `dump` command, I set up a manual backup.

This could lead to potentially corrupted data if I happen to backup at
the exact same time as a push to a repository. However given the
frequency of backups planned, I assume that most of them will be fine.

services/gitea.nix

@@ -38,6 +38,11 @@ in
         type = "postgres"; # Automatic setup
         user = "git"; # User needs to be the same as gitea user
       };
+
+      # NixOS module uses `gitea dump` to backup repositories and the database,
+      # but it produces a single .zip file that's not very backup friendly.
+      # I configure my backup system manually below.
+      dump.enable = false;
     };
 
     users.users.git = {
@@ -61,5 +66,12 @@ in
 
       locations."/".proxyPass = "http://localhost:${toString cfg.port}/";
     };
+
+    my.services.backup = {
+      paths = [
+        config.services.gitea.lfs.contentDir
+        config.services.gitea.repositoryRoot
+      ];
+    };
   };
 }