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

README.md

@@ -1,3 +1,44 @@
 # benvin-utils
 
-Monorepo of small single-purpose CLI tools sharing a common library
+A monorepo of small, single-purpose command-line tools. Each tool is its own
+directory (a `package main`); shared code lives under [`common/`](./common) so
+tools reuse the same TUI primitives and Kubernetes client bootstrapping instead
+of copy-pasting them.
+
+```
+benvin-utils/
+├── common/          # shared library, imported by tools
+│   ├── tui/         #   direction markers, style palette, padding/layout helpers
+│   └── kube/        #   in-cluster→kubeconfig client loading
+├── podgap/          # tool: pod requests/limits vs actual usage (live TUI)
+└── Makefile         # auto-discovers tools — no edits when you add one
+```
+
+## Tools
+
+| Tool | What it does |
+|------|--------------|
+| [`podgap`](./podgap) | Live TUI comparing pod CPU/memory **requests & limits vs actual usage**, with ▲/▼ change markers. |
+
+## Build & install
+
+Tools are auto-discovered (any directory with a `package main`), so the targets
+below need no editing when you add a new tool.
+
+```sh
+make all            # build every tool into ./bin
+make podgap         # build just one tool into ./bin/podgap
+make install        # go install every tool into $GOBIN (or $GOPATH/bin)
+make test           # run all tests
+make list           # list discovered tools
+make help           # show all targets
+```
+
+## Adding a new tool
+
+1. `mkdir mytool && $EDITOR mytool/main.go` with `package main`.
+2. Import shared helpers as needed:
+   `git.unkin.net/unkin/benvin-utils/common/tui`,
+   `git.unkin.net/unkin/benvin-utils/common/kube`.
+3. That's it — `make mytool`, `make all`, and `make install` pick it up
+   automatically.