docs(webcam): portal/Flatpak IR gap is v4l2-only (#71)

Ship the recommended document-only path: WirePlumber hideIrSensor acts
on the v4l2 monitor only; libcamera / xdg-desktop-portal / Flatpak
camera pickers can still list the internal IR sensor.

- HARDWARE.md §7: dual-sensor subsection (scope, workaround, deferred)
- ROADMAP § Webcam: ✓ #71; (b)/(c) stay hardware-gated
- README option row + HARDWARE-QUEUE T14s check for (b)/(c)
- Close BACKLOG #71; no libcamera rules

Verified: V0 (docs only).

README.md

@@ -279,7 +279,7 @@ option, e.g. `services.easyeffects.enable = lib.mkForce false;` — see
 | `nomarchy.hardware.fingerprint.pam` | `false` | Opt-in: use the fingerprint for login + sudo (PAM) |
 | `nomarchy.hardware.npu.enable` | `false` | Opt-in/experimental: load the on-die NPU driver (`amdxdna`/`intel_vpu`); userspace runtime is BYO |
 | `nomarchy.hardware.latestKernel` | `false` | Opt-in: ship `linuxPackages_latest` instead of the default kernel — for very new hardware whose drivers landed recently |
-| `nomarchy.hardware.camera.hideIrSensor` | `false` | Hide a dual-sensor webcam's IR node from PipeWire so apps only ever see the colour camera (the "second, dark Integrated Camera"); installer-set on a paired RGB+IR webcam. `/dev/video*` stays open, so Howdy-style face unlock still works; `.irMatch` overrides the IR-name regex |
+| `nomarchy.hardware.camera.hideIrSensor` | `false` | Hide a dual-sensor webcam's IR node from PipeWire's **v4l2** path so apps only ever see the colour camera (the "second, dark Integrated Camera"); installer-set on a paired RGB+IR webcam. `/dev/video*` stays open, so Howdy-style face unlock still works; `.irMatch` overrides the IR-name regex. Does **not** hide IR from libcamera / portal / Flatpak pickers — see [HARDWARE.md §7](docs/HARDWARE.md) |
 | `nomarchy.hardware.i2c.enable` | `false` | I2C devices support — access to `/dev/i2c-*` (RGB controllers, sensors, DDC/CI monitor control) |
 | `nomarchy.hardware.i2c.ddcci` | `false` (distro default: **`true`**) | the ddcci-driver kernel module, exposing external monitors as standard backlight devices via DDC/CI so brightness keys and swayosd natively control them |
 | `nomarchy.services.tailscale.enable` | `false` | Opt-in: Tailscale mesh VPN — the login user is made the operator, so `tailscale up/down/set` and the System › VPN menu work without sudo |