feat(home): re-add gitleaks

Assisted-by: DeepSeek Harness (deepseek-flash)

home/base/tui/dev-tools.nix

@@ -35,6 +35,9 @@
     # Automatically trims your branches whose tracking remote refs are merged or gone
     # It's really useful when you work on a project for a long time.
     git-trim
+
+    # Scan git repositories and history for accidentally committed secrets.
+    gitleaks
   ];
 
   programs = {