Terminal: Das prompt, dprompt and dbanner (0.9.1)

- das-shell 0.1.0: the Das two-line bash prompt by default (replaces the
  PS1 of Void's skel .bashrc once), dprompt (Textual prompt builder with
  presets and live preview) and dbanner (SSH login banner editor: canvas
  tools, fields with values, widgets, das-banner service for cached ones,
  Das OS logo and tryzub pictures). Python tests in make test.
- das-server 0.3.0 depends on das-shell; the server installer mentions
  dprompt and dbanner; the desktop image includes it.
- run-qemu.sh forwards the guest's SSH to localhost:2222.
- Hardware fixes: Ventoy menu icon, boot menu titles "Das OS <version>".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

srcpkgs/das-shell/files/prompt-lib.sh

@@ -0,0 +1,53 @@
+# Functions behind the Das OS bash prompt (see dprompt). Sourced by
+# /etc/bash/bashrc.d/das-prompt.sh and by the prompt.sh files dprompt writes.
+# shellcheck shell=bash
+
+# Colors when the terminal has at least 8 of them
+__das_has_color() {
+	case $TERM in
+	*color* | xterm* | rxvt* | screen* | tmux* | linux | alacritty | foot* | kitty*) return 0 ;;
+	esac
+	[[ $(tput colors 2>/dev/null) -ge 8 ]]
+}
+
+# Sets __das_git to the branch (or short commit) and "*" when there are changes
+__das_git_info() {
+	command -v git >/dev/null || return 1
+	local branch
+	branch=$(git symbolic-ref --short -q HEAD 2>/dev/null || git rev-parse --short -q HEAD 2>/dev/null) || return 1
+	[[ -n $branch ]] || return 1
+	if [[ -n $(git status --porcelain -uno 2>/dev/null | head -c1) ]]; then
+		branch+="*"
+	fi
+	__das_git=$branch
+}
+
+# Sets __das_jobs to the number of background jobs; fails when there are none
+__das_jobs_count() {
+	local count='\j'
+	__das_jobs=${count@P}
+	((__das_jobs > 0))
+}
+
+# Runs first in PROMPT_COMMAND: keeps the exit status for the prompt and fills
+# the variables of its conditional parts
+__das_prompt_hook() {
+	__das_rc=$?
+	# Void's /etc/skel/.bashrc sets its own PS1 after /etc/bash/bashrc.d: put
+	# the Das OS one back, once, unless the user has a PS1 of their own
+	if [[ -n ${__das_ps1+set} ]]; then
+		[[ $PS1 == '[\u@\h \W]\$ ' ]] && PS1=$__das_ps1
+		unset __das_ps1
+	fi
+	declare -F __das_prompt_dynamic >/dev/null && __das_prompt_dynamic
+	return "$__das_rc"
+}
+
+__das_prompt_install() {
+	__das_ps1=$PS1
+	local cmd
+	for cmd in "${PROMPT_COMMAND[@]}"; do
+		[[ $cmd == __das_prompt_hook ]] && return 0
+	done
+	PROMPT_COMMAND=(__das_prompt_hook "${PROMPT_COMMAND[@]}")
+}