Initial benvin-utils monorepo with podgap tool

Add a monorepo for small single-purpose CLI tools that share a common
library, so tools reuse TUI primitives and Kubernetes client bootstrapping
instead of duplicating them.

- common/tui: direction markers, style palette, width-aware padding/layout
- common/kube: in-cluster→kubeconfig client loading + core/metrics clients
- podgap: live TUI comparing pod requests/limits vs actual usage, with
  up/down markers showing per-pod change since the last refresh
- Makefile auto-discovers tool directories: make <tool> | all | install

.gitignore

@@ -0,0 +1 @@
+/bin/