feat: Jellyfin media server

modules/nixos/impermanence.nix

@@ -38,6 +38,28 @@ in {
           Name of the group whose members have access to the persist directory.
         '';
       };
+
+      cache = {
+        directories = mkOption {
+          description = ''
+            While functionally identical to `directories` (at the moment),
+            `cache.directories` carries additional semantics: these directories
+            /can/ be erased, but typically /shouldn't/ be.
+          '';
+          default = [];
+          type = types.listOf types.anything;
+        };
+
+        files = mkOption {
+          description = ''
+            While functionally identical to `files` (at the moment),
+            `cache.files` carries additional semantics: these files /can/ be
+            erased, but typically /shouldn't/ be.
+          '';
+          default = [];
+          type = types.listOf types.anything;
+        };
+      };
     };
   };
 
@@ -72,8 +94,8 @@ in {
     programs.fuse.userAllowOther = true;
 
     environment.persistence."${cfg.persistDirectory}/root" = {
-      directories = cfg.directories;
-      files = cfg.files;
+      directories = cfg.directories ++ cfg.cache.directories;
+      files = cfg.files ++ cfg.cache.files;
     };
   };
 }