Delete old fp16mixed names + retired medium dit_bf16.trt (fp16 rename shipped)

Rename fp16mixed->fp16 DiT/T5Gemma engines+onnx (copies; deletes follow after code merge)

Remove redundant w8_bf16 engines (int8 weights fold to bf16 at build → identical size/speed to the bf16 baseline)

Add sm_120 TRT engines (AOT SWA, wide profile) for the quantized tiers

sm_120 sa3-m: add the fp8 medium-DiT tier (176 fp8 GEMM + 96 bf16 fused MHA, 1.43-1.95x vs fp16mixed) (#7)

sm_120 SAME-L: AOT (graph-capturable) engines + tensorRT/README.md (#6)

Fix the bf16 medium DiT: bake RoPE's tables into the graph (clipping 3.112% -> 0.014%) (#5)

Rebuild medium DiT fp16-mixed engines (sm_90 + new sm_120): attention now fuses, 4.3x faster (#4)