feat(first-boot): post-install hardware hints — one self-gated toast, once

After the #81 "you're set" card, at most one additional "Hardware tips"
toast: a Firmware line when fwupdmgr is on PATH, a Fingerprint line when
fprintd-list is (VISION § B). One-shot marker settings.hardwareHintsShown,
in-checkout like firstBootShown. When no tooling matches, the marker is
deliberately left unset — the re-check costs a command -v per session,
and a later-enabled fwupd or newly-added reader still gets its hint once.
Never a permanent nag; live-ISO gate covers the new stage too.

Lives inside nomarchy-first-boot: the card's semantics are unchanged
(retry loop, exit 1 so a failed notify retries next login, marker only
after success); hints run only once the card has landed. Docs: README
option row, HARDWARE.md hint paragraphs, VISION § B checked off.

Verification: V2 — shellcheck clean, nix flake check --no-build green,
nix build .#checks.x86_64-linux.first-boot green (bare node silent →
fwupdmgr appears → fires once → silent again → live-ISO still skips).
Real toast rendering is the same session surface as the proven #81 card.
Implementation by a Sonnet subagent; design and review on Fable.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -257,7 +257,7 @@ two tables below are split along exactly that line.
 | `nomarchy.swaync.enable` | `true` | swaync notifications, themed |
 | `nomarchy.batteryNotify.enable` | `true` | Low-battery toasts at the bar's thresholds — 25% low, 10% critical (stays up until dismissed); silent no-op on machines without a battery |
 | `nomarchy.dockAudio.enable` | `true` | On a fresh external-monitor plug, PipeWire/WirePlumber are reprobed after hardware settles and the highest-priority available HDMI/DP/USB sink becomes default, with a toast and journal result. A later manual speaker choice sticks until the next physical plug; unplug falls back to built-in. Manual route: System › Audio |
-| `nomarchy.firstBootWelcome.enable` | `true` | One dismissible “you're set” toast on the first session (SUPER+M / SUPER+T / SUPER+? + network pointer); marker is `settings.firstBootShown` in the flake checkout |
+| `nomarchy.firstBootWelcome.enable` | `true` | One dismissible “you're set” toast on the first session (SUPER+M / SUPER+T / SUPER+? + network pointer); marker is `settings.firstBootShown` in the flake checkout. Also fires at most one follow-up “Hardware tips” toast pointing at System › Firmware / Fingerprint when `fwupdmgr` / `fprintd-list` are on PATH (`settings.hardwareHintsShown`) |
 | `nomarchy.idle.enable` | `true` | hyprlock + hypridle (lock 5 min; display off 10 min in every dock/lid state — input wakes it compositor-side, #127; suspend 15 min battery-only via `nomarchy-suspend`) |
 | `nomarchy.idle.fingerprint` | `false` | Unlock the lock screen with a fingerprint as well as the password, and say so on the input field. Set it alongside `nomarchy.hardware.fingerprint.pam` in system.nix: hyprlock is configured from Home Manager, which cannot read the NixOS option — and hyprlock does **not** take a fingerprint through PAM at all (its PAM stack runs only on submit), so it uses its own fprintd backend that this switch turns on |
 | `nomarchy.yazi.enable` | `true` | yazi TUI file manager, themed + curated plugins |