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

common/kube/kube.go

@@ -0,0 +1,54 @@
+// Package kube provides shared Kubernetes client bootstrapping for the tools in
+// benvin-utils: a single loader that works both in-cluster and from a local
+// kubeconfig, plus a helper that returns the core and metrics clients together.
+package kube
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	metricsv "k8s.io/metrics/pkg/client/clientset/versioned"
+)
+
+// LoadConfig resolves a *rest.Config, preferring in-cluster credentials, then
+// the explicit path, then $KUBECONFIG, then ~/.kube/config.
+func LoadConfig(explicit string) (*rest.Config, error) {
+	if cfg, err := rest.InClusterConfig(); err == nil {
+		return cfg, nil
+	}
+	path := explicit
+	if path == "" {
+		path = os.Getenv("KUBECONFIG")
+	}
+	if path == "" {
+		if home, err := os.UserHomeDir(); err == nil {
+			path = filepath.Join(home, ".kube", "config")
+		}
+	}
+	cfg, err := clientcmd.BuildConfigFromFlags("", path)
+	if err != nil {
+		return nil, fmt.Errorf("load kubeconfig %q: %w", path, err)
+	}
+	return cfg, nil
+}
+
+// Clients returns the core and metrics clientsets for the resolved config.
+func Clients(explicit string) (kubernetes.Interface, metricsv.Interface, error) {
+	cfg, err := LoadConfig(explicit)
+	if err != nil {
+		return nil, nil, err
+	}
+	core, err := kubernetes.NewForConfig(cfg)
+	if err != nil {
+		return nil, nil, fmt.Errorf("core client: %w", err)
+	}
+	mc, err := metricsv.NewForConfig(cfg)
+	if err != nil {
+		return nil, nil, fmt.Errorf("metrics client: %w", err)
+	}
+	return core, mc, nil
+}

common/tui/tui.go

@@ -0,0 +1,86 @@
+// Package tui holds small, reusable terminal-UI primitives shared across the
+// tools in benvin-utils: direction markers, a common style palette, and
+// width-aware padding/truncation helpers that respect ANSI styling.
+package tui
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+// Shared style palette. Tools should prefer these so every benvin-utils TUI
+// looks consistent.
+var (
+	Header = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("15")).Background(lipgloss.Color("240"))
+	Title  = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("87"))
+	Dim    = lipgloss.NewStyle().Foreground(lipgloss.Color("244"))
+	Up     = lipgloss.NewStyle().Foreground(lipgloss.Color("203")) // a rising value = red-ish
+	Down   = lipgloss.NewStyle().Foreground(lipgloss.Color("84"))  // a falling value = green
+	Hot    = lipgloss.NewStyle().Foreground(lipgloss.Color("203")) // over threshold
+	Warn   = lipgloss.NewStyle().Foreground(lipgloss.Color("214")) // approaching threshold
+	Err    = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("203"))
+)
+
+// Marker glyphs for direction-of-change indicators.
+const (
+	GlyphUp   = "▲"
+	GlyphDown = "▼"
+	GlyphFlat = "·"
+)
+
+// Arrow renders a direction marker: 1 = up (▲), -1 = down (▼), 0 = flat (·).
+func Arrow(dir int) string {
+	switch {
+	case dir > 0:
+		return Up.Render(GlyphUp)
+	case dir < 0:
+		return Down.Render(GlyphDown)
+	default:
+		return Dim.Render(GlyphFlat)
+	}
+}
+
+// Sign reports whether d is positive (1), negative (-1), or zero (0). It is the
+// usual companion to Arrow when comparing a new sample against a previous one.
+func Sign[T int | int64 | float64](d T) int {
+	switch {
+	case d > 0:
+		return 1
+	case d < 0:
+		return -1
+	default:
+		return 0
+	}
+}
+
+// Pad right-pads plain (unstyled) text to width w, truncating if longer.
+func Pad(s string, w int) string {
+	if len(s) > w {
+		s = s[:w]
+	}
+	return s + strings.Repeat(" ", w-len(s))
+}
+
+// PadVisible right-pads a possibly ANSI-styled cell to width w using its visible
+// (rendered) width, so styled cells still align in a table.
+func PadVisible(s string, w int) string {
+	if vis := lipgloss.Width(s); vis < w {
+		return s + strings.Repeat(" ", w-vis)
+	}
+	return s
+}
+
+// Truncate shortens s to at most n runes, adding an ellipsis when it cuts.
+func Truncate(s string, n int) string {
+	if n <= 0 {
+		return ""
+	}
+	if len(s) <= n {
+		return s
+	}
+	if n == 1 {
+		return "…"
+	}
+	return s[:n-1] + "…"
+}