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>

common/ham-radio.nix

@@ -0,0 +1,8 @@
+# ABOUTME: Ham radio tools profile for amateur radio operators.
+# ABOUTME: Provides CLI tools for logging and processing ham radio contacts.
+{ pkgs, ... }:
+{
+  environment.systemPackages = [
+    pkgs.custom.flecli
+  ];
+}