ci: move validate maintainers logic to lib

Allow easily running the individual checks outside of GHA for easier
testing/modification.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

lib/python/check-duplicate-maintainers.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+"""
+Check for duplicate maintainers between home-manager and nixpkgs
+
+This script compares the maintainers in home-manager with those in nixpkgs
+to identify duplicates that should be removed from home-manager.
+"""
+
+import json
+import subprocess
+import sys
+
+
+def main():
+    print("🔍 Checking for duplicate maintainers between HM and nixpkgs...")
+
+    # Get home-manager maintainers
+    hm_result = subprocess.run(['nix', 'eval', '--file', 'modules/lib/maintainers.nix', '--json'],
+                              capture_output=True, text=True, check=True)
+    hm_maintainers = json.loads(hm_result.stdout)
+    hm_github_users = set()
+    for name, data in hm_maintainers.items():
+        if 'github' in data:
+            hm_github_users.add(data['github'])
+
+    # Get nixpkgs maintainers
+    nixpkgs_result = subprocess.run(['nix', 'eval', 'nixpkgs#lib.maintainers', '--json'],
+                                   capture_output=True, text=True, check=True)
+    nixpkgs_maintainers = json.loads(nixpkgs_result.stdout)
+    nixpkgs_github_users = set()
+    for name, data in nixpkgs_maintainers.items():
+        if isinstance(data, dict) and 'github' in data:
+            nixpkgs_github_users.add(data['github'])
+
+    # Find duplicates
+    duplicates = hm_github_users.intersection(nixpkgs_github_users)
+
+    if duplicates:
+        print(f'❌ Found {len(duplicates)} duplicate maintainers between HM and nixpkgs:')
+        for github_user in sorted(duplicates):
+            # Find the HM attribute name for this github user
+            hm_attr = None
+            for attr_name, data in hm_maintainers.items():
+                if data.get('github') == github_user:
+                    hm_attr = attr_name
+                    break
+            print(f'  - {github_user} (HM attribute: {hm_attr})')
+        print()
+        print('These maintainers should be removed from HM maintainers file to avoid duplication.')
+        print('They can be referenced directly from nixpkgs instead.')
+        sys.exit(1)
+    else:
+        print('✅ No duplicate maintainers found')
+
+
+if __name__ == "__main__":
+    main()