add nexus flatpak reverse proxy

clients/quadraticserver/nexus.nix

@@ -1,4 +1,21 @@
 {
-  services.caddy.virtualHosts."nexus.federated.nexus".extraConfig =
-    "redir https://git.federated.nexus/Nexus/nexus{uri} permanent";
+  services.caddy.virtualHosts."nexus.federated.nexus".extraConfig = ''
+    handle_path /flatpak/* {
+      rewrite * /nexus{path}
+
+      reverse_proxy https://henry-hiles.github.io {
+        header_up Host {upstream_hostport}
+      }
+
+      @immutable path /objects/* /deltas/*
+      header @immutable >Cache-Control "public, max-age=31536000, immutable"
+
+      @mutable path /summary /summary.sig /refs/* /appstream/*
+      header @mutable >Cache-Control "no-cache"
+    }
+
+    handle {
+      redir https://git.federated.nexus/Nexus/nexus{uri} permanent
+    }
+  '';
 }