feat(quickshell): add dense telemetry bar

tools/quickshell-preview/render.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(git -C "$(dirname "${BASH_SOURCE[0]}")" rev-parse --show-toplevel)"
+tool_dir="$repo_root/tools/quickshell-preview"
+shell_root="$repo_root/dotfiles/quickshell"
+image="homelab-quickshell-preview:qsmcp-76b1b008"
+
+component="${1:-tests/HeadlessSmoke.qml}"
+output="${2:-${TMPDIR:-/tmp}/homelab-quickshell-preview/smoke.png}"
+width="${3:-720}"
+height="${4:-120}"
+
+if ! docker info >/dev/null 2>&1; then
+    echo "error: Docker-compatible daemon is unavailable" >&2
+    exit 69
+fi
+
+case "$output" in
+    /*) ;;
+    *) output="$PWD/$output" ;;
+esac
+
+output_dir="$(dirname "$output")"
+output_name="$(basename "$output")"
+mkdir -p "$output_dir"
+
+container_id=""
+cleanup() {
+    if [[ -n "$container_id" ]]; then
+        docker rm --force "$container_id" >/dev/null 2>&1 || true
+    fi
+}
+trap cleanup EXIT
+
+docker build --tag "$image" --file "$tool_dir/Dockerfile" "$tool_dir"
+
+container_id="$(docker create \
+    --network none \
+    --tmpfs /tmp:rw,noexec,nosuid,size=256m \
+    "$image" \
+    "$component" \
+    --width "$width" \
+    --height "$height" \
+    --dpr 1 \
+    --padding 0 \
+    --background solid \
+    --bg '#0a0a0a' \
+    --out "/output/$output_name")"
+
+# docker cp streams files through the API, so this works with rootless and
+# remote daemons whose filesystem cannot see the client's repository path.
+docker cp "$shell_root/." "$container_id:/workspace/quickshell"
+docker start --attach "$container_id"
+docker cp "$container_id:/output/$output_name" "$output"
+
+test -s "$output"
+printf 'rendered=%s\n' "$output"