feat: container management tools in tools/

Shell scripts for build, start, stop, restart, nuke, logs, status.
Shared helpers in _common.sh (colours, compose detection, project root).
Updated CHEATSHEET.md with new tool references.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/restart

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+# Stop, rebuild, and start the derp container.
+# Usage: tools/restart [--no-cache]
+
+# shellcheck source=tools/_common.sh
+source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/_common.sh"
+
+args=()
+[[ "${1:-}" == "--no-cache" ]] && args+=("--no-cache")
+
+"$SCRIPT_DIR/stop"
+echo
+"$SCRIPT_DIR/build" "${args[@]}"
+echo
+"$SCRIPT_DIR/start"