Migrate caddy.json to nix and setup matrix well-known
diff --git a/modules/caddy.nix b/modules/caddy.nix
index 834db88..a861694 100644
--- a/modules/caddy.nix
+++ b/modules/caddy.nix
@@ -1,6 +1,10 @@
 { config, pkgs, lib, ... }: {
   services.caddy.enable = true;
-  services.caddy.configFile = ./caddy/caddy.json;
+  services.caddy.configFile = lib.pipe ./caddy/caddyfile.nix [
+    import
+    builtins.toJSON
+    (pkgs.writeText "caddy.json")
+  ];
   services.caddy.package = pkgs.callPackage ../packages/caddy.nix {
     vendorSha256 = "sha256-3KcoOAB+YkOU8qKM75uQo58/dljRBmP25dionr9r2dc=";
   };