ci(smoke): cover teardown, state transitions and fake hardware

The smoke test only exercised steady-state rendering and killed waybar with
SIGTERM, so whole crash classes were invisible: exit-time use-after-free
(#5182), module state transitions (#5183) and hardware-backed modules (#5179).
Add tiers that hit those paths under ASan (+ _GLIBCXX_ASSERTIONS):

- lib.sh: assert_clean_exit (SIGINT teardown -> checks segfault/abort + ASan
  report emitted during destruction), output hotplug helpers, signal/reload,
  WAYBAR_WRAP hook, opt-in leak detection.
- lifecycle.sh (gating): clean exit, runtime output hotplug (Bar/module
  destroy), toggle/reload churn, fast-interval teardown race (#5182 class).
- fuzz.sh (gating): pathological custom-backend output (empty, nonzero exit,
  invalid JSON, huge, non-UTF8, empty format).
- coverage.sh (gating): every Factory module must be classified for smoke
  coverage; a new unlisted module fails the job (#5179 slipped through).
- modules.sh: also render the whole matrix inside a group; SIGINT teardown per
  module instead of SIGTERM.
- state.sh (best-effort): real mpd driven through an empty queue (#5183) +
  stop/clear; pulseaudio + slider on a null sink.
- hardware.sh (best-effort): backlight, backlight/slider (#5179) and battery
  via umockdev.
- leakcheck.sh (report-only): clean-exit run under LSan.

test/smoke/hardware.sh

@@ -0,0 +1,87 @@
+#!/usr/bin/env bash
+# Tier — fake-hardware coverage via umockdev. Modules that read sysfs/udev
+# (backlight, its slider, battery) can't run in a headless runner, so they were
+# never smoke-tested and a construct/update crash like #5179 (backlight/slider)
+# could ship unseen. umockdev-run intercepts sysfs/udev and feeds waybar a mock
+# device, so the real code path runs under ASan.
+#
+# Best-effort: skipped if umockdev isn't installed. The .umockdev descriptions
+# below may need tuning per distro; keep this continue-on-error in CI.
+#
+# Usage: hardware.sh
+set -euo pipefail
+DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib.sh
+source "$DIR/lib.sh"
+
+if ! command -v umockdev-run >/dev/null; then
+    echo "(umockdev not installed, skipping hardware tier)"; exit 0
+fi
+
+smoke::setup
+smoke::start_compositor
+trap smoke::stop EXIT
+
+fail=0
+
+BL_DEV="$(mktemp --suffix=.umockdev)"
+cat > "$BL_DEV" <<'EOF'
+P: /devices/platform/fake_backlight/backlight/intel_backlight
+E: SUBSYSTEM=backlight
+A: brightness=500
+A: max_brightness=1000
+A: actual_brightness=500
+A: bl_power=0
+EOF
+
+BAT_DEV="$(mktemp --suffix=.umockdev)"
+cat > "$BAT_DEV" <<'EOF'
+P: /devices/platform/fake_battery/power_supply/BAT0
+E: SUBSYSTEM=power_supply
+E: POWER_SUPPLY_NAME=BAT0
+A: type=Battery
+A: present=1
+A: status=Discharging
+A: capacity=55
+A: energy_now=5500000
+A: energy_full=10000000
+A: power_now=1000000
+EOF
+
+# run_mock <name> <umockdev-file> <config-json>
+run_mock() {
+    local name="$1" dev="$2" mod="$3" cfg
+    echo "::group::hardware: $name"
+    cfg="$(mktemp --suffix=.json)"
+    cat > "$cfg" <<EOF
+{ "layer": "top", "position": "top", "height": 30,
+  "modules-center": ["$name"], $mod }
+EOF
+    WAYBAR_WRAP="umockdev-run --device $dev --" smoke::launch_waybar "$cfg" "$DIR/style.css" 5
+    smoke::assert_alive || fail=1
+    smoke::assert_clean || fail=1
+    smoke::stop; WAYBAR_PID=""
+    echo "::endgroup::"
+}
+
+run_mock "backlight"        "$BL_DEV"  '"backlight": {"format":"{percent}%"}'
+run_mock "backlight/slider" "$BL_DEV"  '"backlight/slider": {"min":0,"max":100,"orientation":"horizontal"}'
+run_mock "battery"          "$BAT_DEV" '"battery": {"format":"{capacity}%"}'
+
+# Slider inside a group -- the exact shape from #5179 (box#backlight-group).
+echo "::group::hardware: backlight/slider in a group"
+cfg="$(mktemp --suffix=.json)"
+cat > "$cfg" <<'EOF'
+{ "layer": "top", "position": "top", "height": 30,
+  "modules-center": ["group/bl"],
+  "group/bl": { "modules": ["backlight/slider"] },
+  "backlight/slider": { "min": 0, "max": 100, "orientation": "horizontal" } }
+EOF
+WAYBAR_WRAP="umockdev-run --device $BL_DEV --" smoke::launch_waybar "$cfg" "$DIR/style.css" 5
+smoke::assert_alive || fail=1
+smoke::assert_clean || fail=1
+smoke::stop; WAYBAR_PID=""
+echo "::endgroup::"
+
+[ "$fail" = 0 ] || { echo "::error::hardware tier failed"; exit 1; }
+echo "✓ fake-hardware tier passed"