[BUG] Spectacle/kpipewire segfault in avcodec_send_frame after ffmpeg 8.1.1-2.1 upgrade (znver4 packages need rebuild)

## Summary
Spectacle crashes with SIGSEGV (segfault) when starting/stopping screen recording via PipeWire — `avcodec_send_frame` crash in `libavcodec.so.62` from `ffmpeg 2:8.1.1-2.1`.

## Problem
Spectacle crashes immediately when starting a screen recording (e.g. via PrtSc) or stopping it (Meta+R). The crash is a segfault in the FFmpeg encoding pipeline, specifically in `avcodec_send_frame`, called from `libKPipeWireRecord.so.6` (kpipewire).

This started after `ffmpeg` was upgraded from `2:8.1.1-1.1` to `2:8.1.1-2.1` on May 13, while `kpipewire` and `spectacle` (znver4-optimized packages from `cachyos-extra-znver4`) were built on May 12 against the previous ffmpeg version.

Still images (screenshots) work fine — only video recording is affected.

## Expected behavior
Spectacle should start/stop screen recording without crashing.

## Actual behavior
Segmentation fault (signal 11) in `avcodec_send_frame` (libavcodec.so.62). No video recording is possible.

## Reproduction steps
1. Install CachyOS with KDE Plasma (znver4 variant).
2. Ensure ffmpeg 2:8.1.1-2.1, kpipewire 6.6.5-1.1, spectacle 1:6.6.5-1.1 are installed.
3. Press PrtSc → select "Record region" (or any video recording option).
4. **Result:** Spectacle disappears/crashes immediately.

## Stack trace (from coredump)
```
Stack trace of thread 26431:
#0 libavcodec.so.62 + 0x729a18
#1 libavcodec.so.62 + 0x3bde7c
#2 avcodec_send_frame (libavcodec.so.62 + 0x3be127)
#3 libKPipeWireRecord.so.6 + 0x12586
#4 Qt6Core + 0x1f081b
#5 PipeWireSourceStream::stateChanged (libKPipeWire.so.6 + 0x19b54)
```

## System info
- **OS:** CachyOS (rolling), znver4
- **Kernel:** 7.0.10-2-cachyos
- **Session:** Wayland
- **Packages:**
- ffmpeg 2:8.1.1-2.1 (installed 2026-05-09, upgraded to -2.1 on 2026-05-13)
- kpipewire 6.6.5-1.1 (built 2026-05-12)
- spectacle 1:6.6.5-1.1 (built 2026-05-12)
- pipewire 1:1.6.6-1.1

## Possible cause
The `kpipewire` and `spectacle` znver4-optimized packages in `cachyos-extra-znver4` were built against `ffmpeg 2:8.1.1-1.1` and likely need to be rebuilt against the current `ffmpeg 2:8.1.1-2.1`. The FFmpeg ABI (`libavcodec.so.62`) minor-version bump may have introduced behavioral changes that break `avcodec_send_frame` with the parameters used by `KPipeWireRecord`.

## Workaround (temporary)
Installing the standard `extra` repo versions (`kpipewire` and `spectacle` from `extra` instead of `cachyos-extra-znver4`) may help.

Start by reproducing screen recording with ffmpeg 2:8.1.1-2.1 and the listed znver4 kpipewire and spectacle packages, then inspect their package build inputs and the coredump stack trace around avcodec_send_frame. Done means the affected znver4 packages are rebuilt against the current ffmpeg and starting or stopping recording no longer crashes.

Written by the indexing model from the issue text.