## What's wrong

On hybrid-GPU laptops (Intel iGPU + NVIDIA dGPU), `omarchy capture screenrecording` silently fails to start a recording when the target is an external monitor wired to the dGPU. Only the laptop panel (iGPU) records. Reported by @Mohamedkrms in #7479.

## Repro

Hybrid laptop (e.g. Intel iGPU + NVIDIA dGPU), external monitor on HDMI/DP wired to the dGPU. Start a screen recording targeting the external monitor (fullscreen on it, or a region on it). No recording starts — nothing is written to `~/Videos`.

## Root cause

`gpu-screen-recorder`'s **kms backend connects to one DRM card** — the one driving the internal panel (the iGPU). A dGPU-driven external monitor's connector isn't visible to that card, so gsr logs:

```
gsr error: gsr_capture_kms_start: failed to find monitor by name "DP-1"
gsr error: gsr_capture_start failed
```

and exits without producing a file. The script's wait loop then sees the process dead and silently gives up — no recording, no message.

gsr exposes **no capture-time card selector** (only `--list-capture-options [card_path]`), so the kms backend can't be pointed at the dGPU card. The portal backend (`-w portal`, xdg-desktop-portal ScreenCast) is the documented path for "monitors driven by external GPUs" (the script already notes this in its `OMARCHY_SCREENRECORD_USE_PORTAL` opt-in), but it pops a picker and can hit EGL DMA-BUF modifier issues on some setups.

Same root cause as the closed #4804 and #4834.

## Immediate workaround (no code change)

Set the portal backend for the session:

```bash
mkdir -p ~/.config/uwsm/env.d
echo 'OMARCHY_SCREENRECORD_USE_PORTAL=true' > ~/.config/uwsm/env.d/capture
```

Then re-login so uwsm picks it up. This routes recordings through the portal picker, which can capture dGPU-driven external monitors. (Trade-off: the laptop-screen recordings also go through the portal picker instead of the kms/slurp path.)

## Planned fix

Auto-fallback: when the kms backend fails to start (gsr exits without producing the output file), retry once via the portal backend with a notification, so external monitors work without the env var. This keeps the fast kms path for the laptop panel and only invokes the portal picker when kms can't see the target monitor.

A fix is in progress in a separate PR (linked below). It needs verification on a hybrid + external-monitor setup — if you can test, please comment.