### What happened

Every screen recording made with audio is written at **96 kHz AAC** instead of the 48 kHz that `gpu-screen-recorder` captured.

96 kHz AAC is unusual enough to be poorly supported downstream. DaVinci Resolve reads the container metadata correctly (reports `AAC`, `2ch`, `Sample Rate 96000`) but decodes no samples — the clip imports and the video scrubs and plays fine, while the audio is silent and the timeline waveform is a blank rectangle. It also costs bitrate for no benefit, since the source audio was 48 kHz.

### What I expected

Recordings keep the 48 kHz sample rate they were captured at.

### Root cause

`bin/omarchy-capture-screenrecording`, in `finalize_recording()` (line 271):

```bash
args+=(-af "volume=enable='lt(t,0.4)':volume=0,afade=t=in:st=0.4:d=0.05,loudnorm=I=-14:TP=-1.5:LRA=11")
```

ffmpeg's `loudnorm` analyses at 192 kHz and declares that as its output rate. With no `-ar` on the command, ffmpeg negotiates that rate with the AAC encoder, which caps at its own 96 kHz ceiling — so the finalize pass silently resamples 48 kHz up to 96 kHz.

`gpu-screen-recorder` is not at fault; the file is correct until `finalize_recording()` runs.

### Steps to reproduce

Independent of the recorder — this reproduces with plain ffmpeg:

```bash
# stand in for a gsr recording: 48 kHz AAC
ffmpeg -y -f lavfi -i testsrc=size=320x240:rate=60 \
       -f lavfi -i "sine=frequency=440:sample_rate=48000" \
       -t 3 -c:v libx264 -c:a aac -ar 48000 gsr_sim.mp4

# exactly what finalize_recording() runs
ffmpeg -y -ss 0.1 -i gsr_sim.mp4 -c:v copy \
  -af "volume=enable='lt(t,0.4)':volume=0,afade=t=in:st=0.4:d=0.05,loudnorm=I=-14:TP=-1.5:LRA=11" \
  gsr_finalized.mp4

ffprobe -v error -select_streams a -show_entries stream=codec_name,sample_rate -of csv=p=0 gsr_sim.mp4
ffprobe -v error -select_streams a -show_entries stream=codec_name,sample_rate -of csv=p=0 gsr_finalized.mp4
```

Result:

```
gsr output (before finalize):  aac,48000
after finalize_recording():    aac,96000
same chain minus loudnorm:     aac,48000   # isolates loudnorm as the cause
```

Or end to end: `omarchy screenrecord --fullscreen --with-desktop-audio`, stop it, then ffprobe the file.

### Suggested fix

Pin the output rate — add `-ar 48000` to that invocation. Loudness normalization is unaffected; a -21.1 dB source still lands at -13.6 dB against the -14 LUFS target.

Happy to open a PR.

### System details

- Omarchy 4.0.2-1
- gpu-screen-recorder 6.0.1
- ffmpeg n9.0.1
- Arch Linux, kernel 7.1.9-arch1-2
- AMD Radeon RX 7900 XTX (amdgpu)