refactor: reorganize server modules

- Moved each individual service definition into a dedicated `services/`
  directory under every server module (e.g.
`modules/servers/bragi/services/`).
- Updated the corresponding `default.nix` files to import the renamed
  service modules from the new location.
- Applied the same changes across all server modules, ensuring
  the API and import paths remain consistent.

modules/servers/freyja/services/immich.nix

@@ -0,0 +1,39 @@
+{...}: {
+  services.immich = {
+    enable = true;
+    port = 2283;
+    host = "127.0.0.1";
+    accelerationDevices = ["/dev/dri/renderD128"];
+  };
+
+  users.users.immich.extraGroups = ["video" "render"];
+
+  services.traefik.dynamicConfigOptions.http = {
+    services.immich.loadBalancer.servers = [
+      {
+        url = "http://localhost:2283";
+      }
+    ];
+
+    routers.immich = {
+      rule = "Host(`immich.cronyakatsuki.xyz`)";
+      tls = {
+        certResolver = "porkbun";
+      };
+      service = "immich";
+      entrypoints = "websecure";
+    };
+  };
+
+  services.postgresqlBackup = {
+    enable = true;
+    databases = [
+      "immich"
+    ];
+  };
+
+  services.restic.backups = {
+    local.paths = ["/var/lib/immich" "/var/backup/postgresql"];
+    server.paths = ["/var/lib/immich" "/var/backup/postgresql"];
+  };
+}