readme: add demo gif

Recording script committed at assets/demo.tape — renders with
charmbracelet/vhs against a real Linux+Firecracker host.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -2,6 +2,8 @@
 
 One-command development sandboxes on Firecracker microVMs.
 
+![banger demo](assets/banger.gif)
+
 Spin up a clean Linux VM with your repo and tooling preloaded, drop
 into ssh, and tear it down — all from one command. banger is built
 for the dev loop, not the server use case: guests are short-lived,

assets/demo.tape

@@ -0,0 +1,112 @@
+# banger hero demo — VHS tape
+# Render with: vhs assets/demo.tape
+
+Output assets/banger.gif
+
+Require banger
+Require ssh
+Require curl
+
+Set Shell "bash"
+Set FontSize 14
+Set LineHeight 1.4
+Set Width 1200
+Set Height 720
+Set Padding 20
+Set Theme "Catppuccin Frappe"
+Set TypingSpeed 66ms
+
+# Off-camera reset: enable bash syntax highlighting via ble.sh, prompt
+# styling, drop any prior demo VM, and clear the screen.
+Hide
+Type "source ~/.local/share/blesh/ble.sh --noattach"
+Enter
+Sleep 200ms
+Type "bleopt complete_auto_complete= complete_auto_history="
+Enter
+Sleep 100ms
+Type `export PS1="\n$PS1"`
+Enter
+Sleep 200ms
+Type "[[ ${BLE_VERSION-} ]] && ble-attach"
+Enter
+Sleep 400ms
+Type "ble-face -s syntax_error fg=red"
+Enter
+Sleep 100ms
+Type "banger vm kill demo 2>/dev/null; banger vm delete demo 2>/dev/null; clear"
+Enter
+Sleep 500ms
+Show
+
+Type "banger vm run --nat --name demo"
+Enter
+Wait+Line /demo:~#/
+Sleep 1.4s
+
+Type "uname -a"
+Enter
+Sleep 1.4s
+
+Type "exit"
+Enter
+Wait
+Sleep 700ms
+
+Type "banger vm list"
+Enter
+Wait
+Sleep 1.8s
+
+Type "ssh demo.vm"
+Enter
+Wait+Line /demo:~#/
+Sleep 500ms
+
+Type "touch foo bar baz"
+Enter
+Sleep 700ms
+
+Type "ls"
+Enter
+Sleep 1.4s
+
+Type "exit"
+Enter
+Sleep 700ms
+
+Type "banger vm stop demo"
+Enter
+Wait
+Sleep 1s
+
+Type "banger vm start demo"
+Enter
+Wait
+Sleep 1s
+
+Type "banger vm exec demo -- ls"
+Enter
+Wait
+Sleep 1.4s
+
+Type "banger vm exec demo -- docker run -d -p 80:80 nginx"
+Enter
+Wait
+Sleep 1.6s
+
+Type "banger vm ports demo"
+Enter
+Wait
+Sleep 2s
+
+Type "curl http://demo.vm"
+Sleep 1.2s
+Enter
+Wait
+Sleep 4s
+
+Type "banger vm kill demo && banger vm delete demo"
+Enter
+Wait
+Sleep 3s