Add ham radio profile with FLEcli package

Introduces a custom packages overlay (pkgs/) for packages not in nixpkgs.
Adds FLEcli v0.1.7 for processing amateur radio logs (SOTA, POTA, WWFF).
Enables ham-radio profile on beefy.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.nix

@@ -67,6 +67,8 @@
         browser-previews = browser-previews.packages.${prev.stdenv.hostPlatform.system};
       };
 
+      overlay-custom = import ./pkgs;
+
       mkHost =
         system: profile: modules:
         let
@@ -79,7 +81,7 @@
             (
               { config, pkgs, ... }:
               {
-                nixpkgs.overlays = [ overlay-unstable overlay-browser-previews ];
+                nixpkgs.overlays = [ overlay-unstable overlay-browser-previews overlay-custom ];
                 nixpkgs.config.allowUnfree = true;
               }
             )