docs: record the MODE assumption of v_mullit_f32 in TechnicalDebt

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

docs/dev/TechnicalDebt.md

@@ -80,6 +80,7 @@ Throughout the project, every function at every stage either **does exactly what
 - The shader recompiler [ignores `s_setreg_b32`](../../core/shader/recompiler/Translation/src/ScalarInstructions.cpp): writes to MODE (float rounding and denormal controls) and the other hardware registers have no effect, and `s_getreg_b32` reads of the MODE round fields report round to nearest even even after `s_setreg_b32` wrote another mode. The initial round mode from the shader's program registers is not read either.
 - [Shader recompilation](../../core/shader/recompiler/Recompiler.cpp) currently occurs right before it was transferred to Vulkan with caching, but should be moved to the [relinker](../../core/relinker/main.cpp) stage. For this purpose, [shader/recompiler](../../core/shader/recompiler) was written completely independently from [libs/prx](../../core/libs/prx).
 - [v_fma_f64](../../core/shader/recompiler/SpirvBackend/src/SpirvAlu/SpirvAluEmitterFloat64.cpp) is fused exactly only for normal inputs: with a subnormal input it is a separate multiply and add, which rounds twice.
+- [v_mullit_f32](../../core/shader/recompiler/Translation/src/FloatInstructions.cpp) follows the hardware measured with the MODE register at IEEE=1 and denormals kept (a signaling NaN src0 is quieted, a positive denormal src2 counts as positive): the recompiler does not read MODE, so other IEEE/denormal settings are not modelled.
 - The executable file that [relinker](../../core/relinker/elfpatcher/src/windows/WindowsPeWriter.cpp) generates opens the console when launched, which is inconvenient for playability.
 - [libSceJpegEnc](../../core/libs/prx/libSceJpegEnc/Export.cpp) encodes 4:2:2 sampling requests with 4:2:0 chroma subsampling, and grayscale requests as a 3-component JPEG with neutral chroma instead of a single-component one: the [JPEG encoder](../../core/Decoder/Jpeg/src/Jpeg.cpp) (stb) only produces 3-component 4:2:0 and 4:4:4 images.
 - [v_rcp, v_rsq, v_sqrt, v_log, v_exp, v_sin and v_cos](../../core/shader/recompiler/Translation/src/FloatInstructions.cpp) (f32 and f16) use the driver's approximation for finite results, not the console's: the low bits can differ. Only NaN, invalid, zero and infinite results and the exact sin/cos zeros are chosen on the bits. v_sin_f32/v_cos_f32 with inputs beyond ±256 cycles were not compared with the console.