fix: migration first-boot, fingerprint PAM, menus, mic LED

Post-migration annoyances from TuringMachine:

- Force fprintAuth from fingerprint.pam (NixOS defaults it on with fprintd)
- First-boot toast waits for swaync, retries, only marks after success
- Night light status/toggle handles masked units + hyprsunset/wlsunset
- VPN menu: define rofi_menu in nomarchy-vpn (was a silent no-op)
- Left arrow = ↩ Back in list menus; GTK menu contrast via Stylix
- Mic-mute LED udev + sync after wpctl; EasyEffects starts after tray
- Migration guide: HM before GUI login, fingerprint/browser/VPN notes

Verified: flake check --no-build; checks.first-boot; checks.hardware-toggles
(pam=false node). V3 session items pending after user rebuild.

modules/nixos/default.nix

@@ -450,6 +450,17 @@ in
     # users without root. Harmless baseline even if the OSD is disabled.
     services.udev.packages = [ pkgs.swayosd ];
 
+    # Mic-mute LED sysfs nodes (ThinkPad platform::micmute, HDA *::micmute)
+    # default to root-only. PipeWire mute does not drive the kernel's
+    # audio-micmute trigger, so nomarchy-mic-mute writes brightness itself.
+    # Group `video` matches the backlight udev pattern (swayosd) and the
+    # template login user's extraGroups.
+    services.udev.extraRules = lib.mkAfter ''
+      ACTION=="add", SUBSYSTEM=="leds", KERNEL=="*micmute*", \
+        RUN+="${pkgs.coreutils}/bin/chgrp video /sys/class/leds/%k/brightness /sys/class/leds/%k/trigger", \
+        RUN+="${pkgs.coreutils}/bin/chmod g+w /sys/class/leds/%k/brightness /sys/class/leds/%k/trigger"
+    '';
+
     # ── Nix itself ───────────────────────────────────────────────────
     nix = {
       settings = {