docs: the denoiser's Swin block is the L/M template's block

docs/native-kernels.md

@@ -89,6 +89,8 @@ Measured on the RX 9070 XT (gfx1201, RDNA4), Ray Reconstruction preset E, 1280×
 | enc2 | 1.74 | luma, exposure, reduce_sum | 0.05 |
 | hkpn output (translated → native) | 1.44 → 1.00 | **total** | **31.6 → 31.1** |
 
+The denoiser's Swin block is the same block as presets L/M's: `cuda_dldn_engine_swin_enc0_kernel` computes position-only attention `S = bias + Q*Q^T` with no K projection, a 16x16 f16 bias table at 512 bytes per head, and one fused Q/V projection - the score `mma` at line 8406 takes both of its operands from the same accumulator registers, `%r1900`/`%r1920`, through their `cvt.rn.satfinite.e4m3x2.f16x2` at 8126/8129 and 8294/8297. That is `kernels/m/swin_block.h`'s block (`T16 S = bias; k32(S, a0, a0, a1, a1);`), not `kernels/k`'s learned-attention one. So the native denoiser layers can be built by instantiating that template - a prep that permutes the denoiser's own weight image into its slot layout, a parameter struct for the 144-byte block, and the surface stores through `tex_common.h` - rather than by writing a Swin block from scratch.
+
 The eleven Swin layers are 30.2 of those 31.6 ms. They are instruction-bound, not MMA-bound: the compiled `enc0` kernel is 83 373 instructions per thread for 536 FP8 WMMAs (0.6% of the stream), and the frame reaches about 6% of the card's FP8 WMMA peak. The stream is 13 k operand-gather shuffles (`ds_bpermute`/`v_perm`/`permlane`), 15 k packed 16-bit ops from the software `cvt.rn.satfinite.e4m3x2.f16x2` requantization, 9 k selects and 13 k ALU-dependency waits. `D4R_ZLUDA_IMPLICIT_MAX_BLOCK` (256 in the shipped config), `D4R_ZLUDA_SCHED_STRATEGY` and a 128-thread bound move the total by under 3%; a 128-thread bound additionally fails the launches of kernels that use larger blocks, and the whole-module wave64 switch produces no launches at all. Removing the gather and the codec — what a native layer does — is the remaining work.
 
 ## RDNA4