feat(apple): PyroWave Phase 5 — native Metal decode on Mac / Apple TV / iPad (§4.7)

The Apple client now decodes PyroWave natively on the presenter's own MTLDevice —
no MoltenVK, no upstream C++ in the app. Completes and wires up the decoder whose
early working-tree snapshot rode along in 9127c346:

- MetalWaveletShaders.swift: wavelet_dequant + idwt hand-ported from the vendored
  GLSL (STORAGE_MODE 0 only; subgroup scans → 32-wide simdgroups; DCShift spec
  constant → function constant; precision-1 split: fp16 levels 0-1 / fp32 2-4).
- MetalWaveletDecoder.swift: Swift reimplementation of push_packet/decode_packet
  incl. the Phase-4 chunk-aligned window walk (FRAG chains, zeroed missing shards,
  the >half-blocks partial rule), init_block_meta's block-index space, and the
  42-dequant + 13-idwt dispatch structure with encoder-boundary barriers. SOF-dims
  changes rebuild the size-dependent resources, which is also the mid-stream
  resize path. Ring of 4 output plane sets on the presenter's queue.
- Presenter: pf_frag_planar (3xR8, the planar_csc.frag twin) + renderPlanar with
  a shared present tail; ReadyFrame carries an image enum (.video | .planar).
- Stage2Pipeline: a dedicated PyroWave pump — no VideoToolbox machinery, no
  keyframe/re-anchor recovery (all-intra; partials render as localized blur by
  design), newest-frame-index staleness guard for late partials.
- Opt-in: "PyroWave (wired LAN)" codec entry (probe-gated, ≈A13 floor via a real
  kernel-compile probe), selecting it advertises + prefers the codec and forces
  the session SDR (HDR/10-bit/4:4:4 caps dropped, plan contract).
- Core ABI: punktfunk_connection_shard_payload() — the Welcome's negotiated shard
  payload, needed by native decoders to walk chunk-aligned AUs.
- Validation: golden fixtures generated by the host encoder + upstream's own
  decoder (pyrowave_dump_golden, RTX 5070 Ti); the Metal decode PSNR-matches at
  77-88 dB across all planes for dense AND chunk-aligned AUs, and a hole-punched
  partial still decodes. Parser unit tests cover the window walk, FRAG chains,
  broken chains, the half-blocks gate, and the block-index layout.

Tests: apple 134 green (mac; iOS/tvOS build), host 312 w/ pyrowave on .21,
core 148 w/ quic; clippy/fmt clean.

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

clients/apple/Sources/PunktfunkClient/Session/SessionModel.swift

@@ -239,6 +239,18 @@ final class SessionModel: ObservableObject {
             // from these + the soft `preferredCodec`; `resolvedCodec` reflects what it chose.
             var videoCodecs = PunktfunkConnection.codecH264 | PunktfunkConnection.codecHEVC
             if AV1.hardwareDecodeSupported { videoCodecs |= PunktfunkConnection.codecAV1 }
+            // PyroWave (wired LAN) is a pure opt-in: picking it in the codec setting both
+            // advertises the bit and prefers it — the host never auto-selects it, and the
+            // picker only offers it when the Metal decode probe passed (simdgroup floor ≈ A13;
+            // every M-series Mac and the ATV 4K gen 3 pass). The codec is 8-bit 4:2:0 SDR
+            // BT.709 by contract, so the opt-in also drops the HDR/10-bit/4:4:4 caps for this
+            // session — HDR sessions stay HEVC/AV1 (plan §4.7).
+            if preferredCodec == PunktfunkConnection.codecPyroWave, MetalWaveletDecoder.supported {
+                videoCodecs |= PunktfunkConnection.codecPyroWave
+                videoCaps &= ~(PunktfunkConnection.videoCap10Bit
+                    | PunktfunkConnection.videoCapHDR
+                    | PunktfunkConnection.videoCap444)
+            }
             let result = Result { try PunktfunkConnection(
                 host: host.address, port: host.port,
                 width: width, height: height, refreshHz: hz,