fix(client): unused 'decoder label under default features + box the PyroWave backend variant

ci.yml's -D warnings clippy (default features) flagged the labeled block
whose only break lives behind the pyrowave cfg — restructured as cfg'd
let-bindings, no label. Also boxed Backend::PyroWave (the decoder's
pinned create-info hold + plane ring dwarfed the other variants —
clippy::large_enum_variant under the feature).

Both configs strict-clippy clean on .21; 26 tests green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/pf-client-core/src/session.rs

@@ -278,22 +278,23 @@ fn pump(
         welcome_codec = connector.codec,
         "negotiated video codec"
     );
-    let built = 'decoder: {
     // A negotiated PyroWave session decodes on the presenter's device, no FFmpeg —
     // reachable only through the explicit preference above (resolve_codec never
     // auto-picks the bit), so failing loudly here is failing an opted-in experiment.
     #[cfg(all(target_os = "linux", feature = "pyrowave"))]
-        if connector.codec == punktfunk_core::quic::CODEC_PYROWAVE {
+    let built = if connector.codec == punktfunk_core::quic::CODEC_PYROWAVE {
         let mode = connector.mode();
-            break 'decoder match params.vulkan.as_ref() {
+        match params.vulkan.as_ref() {
             Some(vk) => Decoder::new_pyrowave(vk, mode.width, mode.height),
             None => Err(anyhow::anyhow!(
                 "pyrowave session without a presenter device"
             )),
-            };
         }
+    } else {
         Decoder::new(codec_id, &params.decoder, params.vulkan.as_ref())
     };
+    #[cfg(not(all(target_os = "linux", feature = "pyrowave")))]
+    let built = Decoder::new(codec_id, &params.decoder, params.vulkan.as_ref());
     let mut decoder = match built {
         Ok(d) => d,
         Err(e) => {

crates/pf-client-core/src/video.rs

@@ -323,8 +323,9 @@ enum Backend {
     D3d11va(crate::video_d3d11::D3d11vaDecoder),
     /// PyroWave (wired-LAN wavelet codec): pyrowave compute on the presenter's device,
     /// no FFmpeg involvement. No demotion rung — there is no other decoder for it.
+    /// Boxed: the decoder (pinned create-info hold + plane ring) dwarfs the other variants.
     #[cfg(all(target_os = "linux", feature = "pyrowave"))]
-    PyroWave(crate::video_pyrowave::PyroWaveDecoder),
+    PyroWave(Box<crate::video_pyrowave::PyroWaveDecoder>),
     Software(SoftwareDecoder),
 }
 
@@ -573,9 +574,9 @@ impl Decoder {
     #[cfg(all(target_os = "linux", feature = "pyrowave"))]
     pub fn new_pyrowave(vk: &VulkanDecodeDevice, width: u32, height: u32) -> Result<Decoder> {
         Ok(Decoder {
-            backend: Backend::PyroWave(crate::video_pyrowave::PyroWaveDecoder::new(
+            backend: Backend::PyroWave(Box::new(crate::video_pyrowave::PyroWaveDecoder::new(
                 vk, width, height,
-            )?),
+            )?)),
             codec_id: ffmpeg::codec::Id::HEVC,
             vaapi_fails: 0,
             want_keyframe: false,