[perf] Optimize MiniMax-H3 text encoder memory: slim single-tensor forward
contract for the Qwen3-VL conditioner (early return at the layer-50 tap,
-262 MiB peak on top of merged #1711), TextEncoder base relaxed to
Generic[TextEncoderOutputT], and opt-in checkpoint-serialized block-FP8
(new text_encoder_quantization.py + minimax_h3_checkpoint_fp8.py).
Clean merge, no conflicts (PR base c4ad4227c == main's state for all touched
files; the tests/local_tests/minimax_h3/README.md hunk applied cleanly on top
of the #1703 dedupe).
Review status (pr1732.md): the two blockers are sm12x/FP8-only - the cutlass
m%4 crash is on the sm12x route (GB200/sm100 uses trtllm, verified clean at
m=559), and the FP8+cpu-offload gap only matters with FP8 enabled. This stack
keeps text-encoder FP8 OFF for all benches, so neither blocker is reachable.
Will Lin
160f0c9ccf