Use the panel from its own flake (reudy-net/panel)

The panel's code moved to git.reudy.net/reudy-net/panel, which provides a
package and a NixOS module. This config now pulls it in as the `panel`
flake input and only sets services.reudy-panel options, so panel updates
are `nix flake update panel` instead of edits in this repo.

The input uses ssh because the reudy-net org is not visible anonymously.
The generated service, directories, Caddy vhost, routes import and reload
units are unchanged apart from store paths.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UbWSNkXxZhYf7eqHTyx3Bf

flake.nix

@@ -11,6 +11,12 @@
       inputs.nixpkgs.follows = "nixpkgs";
       inputs.darwin.follows = "";
     };
+
+    # The deployment panel (panel.reudy.net), packaged in its own repository.
+    panel = {
+      url = "git+ssh://git@git.reudy.net:14922/reudy-net/panel?ref=main";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
@@ -18,6 +24,7 @@
       nixpkgs,
       vpsadminos,
       agenix,
+      panel,
       ...
     }:
     let
@@ -31,6 +38,7 @@
           { nixpkgs.overlays = [ agenix.overlays.default ]; }
           vpsadminos.nixosModules.container_25_11
           ./configuration.nix
+          panel.nixosModules.default
           ./panel.nix
           ./caddy.nix
           ./authelia.nix