feat(core,host,client): PyroWave datagram-aligned packets + partial-frame delivery (Phase 4, §4.4)

PyroWave AUs now packetize on the negotiated shard payload, so a lost datagram
costs a few wavelet blocks of localized blur rather than a whole frame — and the
client can render an aged-out lossy frame instead of freezing until the next one.

Host (opt-in, PyroWave only):
- The encoder packetizes at the shard payload behind a 4-byte window prefix
  (used-len u16 + kind u16). Whole packets pack into WIN_PACKED windows; a packet
  too large for one shard (PyroWave 32x32 blocks are atomic and can exceed a
  shard) rides a WIN_FRAG_FIRST/CONT/LAST chain. `set_wire_chunking()` joins the
  Encoder trait (forwarded through TrackedEncoder — the silent-no-op trap);
  EncodedFrame.chunk_aligned marks the AU.
- virtual_stream tags the AU with USER_FLAG_CHUNK_ALIGNED and re-applies chunking
  after every encoder (re)build, the adaptive-bitrate rebuild included.

Core:
- USER_FLAG_CHUNK_ALIGNED (0x40) wire bit. Reassembler opt-in
  (set_deliver_partial): a chunk-aligned frame that ages out with holes is handed
  over as Frame{complete:false} — received shards at their exact offsets, missing
  ranges zero-filled — instead of being dropped. Partials age out on a tight 30ms
  fuse (PARTIAL_WINDOW_NS) instead of the 120ms loss window: each frame is
  independently decodable, so an ancient partial has no value in a live stream.
  Newest-wins. A partial still counts as dropped for loss reporting.

Client (PyroWave decode):
- The session opts in when codec == PyroWave. The decoder walks the AU
  window-by-window, skipping zero (missing) windows and reassembling FRAG chains,
  then decodes whatever survived. A newest-decoded-index guard drops partials the
  pump has already moved past (no time-travel present).

Also fixes a redundant-closure clippy nit in the PyroWave planar-present path.

Validated on an RTX 5070 Ti under 2% netem loss with FEC pinned off: 60fps
sustained entirely via partials, e2e 43ms p50 (146ms before the fuse) vs 23ms
lossless, no keyframe-recovery chatter. Tests green: core 149, host 310 + the
GPU-gated encoder smoke (framed-window walk + FRAG reassembly + upstream
round-trip), client 26; clippy clean on the pyrowave feature combos.

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

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

@@ -289,7 +289,12 @@ fn pump(
     let built = if connector.codec == punktfunk_core::quic::CODEC_PYROWAVE {
         let mode = connector.mode();
         match params.vulkan.as_ref() {
-            Some(vk) => Decoder::new_pyrowave(vk, mode.width, mode.height),
+            Some(vk) => Decoder::new_pyrowave(
+                vk,
+                mode.width,
+                mode.height,
+                connector.shard_payload as usize,
+            ),
             None => Err(anyhow::anyhow!(
                 "pyrowave session without a presenter device"
             )),
@@ -324,6 +329,8 @@ fn pump(
     // step, drift) keep the capture-clock latency stats honest — never cached at session start.
     let clock_offset_live = connector.clock_offset_shared();
     let mut total_frames = 0u64;
+    // Newest frame index handed to the decoder — the staleness bar for late partials.
+    let mut newest_decoded_idx: Option<u32> = None;
     let mut window_start = Instant::now();
     let mut frames_n = 0u32;
     let mut bytes_n = 0u64;
@@ -432,7 +439,21 @@ fn pump(
                     }
                     None => next_expected_index = Some(frame.frame_index.wrapping_add(1)),
                 }
-                match decoder.decode(&frame.data) {
+                // A PARTIAL that lost the race (a newer frame already decoded) is pure
+                // time travel — skip it; each PyroWave frame is independent, so nothing
+                // downstream needs it. Completes keep the normal path (reorder is handled
+                // by the continuity gate).
+                if !frame.complete
+                    && newest_decoded_idx
+                        .is_some_and(|n: u32| n.wrapping_sub(frame.frame_index) <= u32::MAX / 2)
+                {
+                    continue;
+                }
+                newest_decoded_idx = Some(match newest_decoded_idx {
+                    Some(n) if frame.frame_index.wrapping_sub(n) > u32::MAX / 2 => n,
+                    _ => frame.frame_index,
+                });
+                match decoder.decode_frame(&frame.data, frame.flags, frame.complete) {
                     Ok(Some(image)) => {
                         // Fold this decoded frame through the shared freeze gate: it reads the AU's
                         // re-anchor wire flags (FLAG_SOF IDR marker / RECOVERY_ANCHOR / RECOVERY_POINT),