Add nvtriton (Triton TileIR backend) to helion Dockerfile (#461)

Install nvtriton wheel from GitHub Release v3.6.0-rc1 after PyTorch,
replacing the upstream triton==3.6.0 that ships with PyTorch cu130.
Set ENABLE_TILE=1 to activate the TileIR compiler backend by default.

Verified on B200 (sm100):
- TileIRDriver activation: OK
- tileiras embedded discovery: OK
- Triton dot kernel (fp16 64x64): max diff 0.0
- Helion matmul (fp16 256x256): max diff 0.0
- IR pipeline: convert-triton-to-cuda-tile → cuda_tile.module confirmed
- Helion test suite (HELION_BACKEND=tileir): 834 passed, 463 skipped, 0 failed

Author: glassmanK

docker/helion.Dockerfile

@@ -50,6 +50,14 @@ RUN sudo uv pip install --system \
     torch \
     --index-url https://download.pytorch.org/whl/cu130
 
+# nvtriton (Triton with TileIR backend — replaces upstream triton)
+RUN curl -L -o /tmp/nvtriton-3.6.0-cp313-cp313-linux_x86_64.whl \
+    https://github.com/triton-lang/Triton-to-tile-IR/releases/download/v3.6.0-rc1/nvtriton-3.6.0-cp313-cp313-linux_x86_64.whl \
+    && sudo uv pip install --system /tmp/nvtriton-3.6.0-cp313-cp313-linux_x86_64.whl \
+    && rm /tmp/nvtriton-3.6.0-cp313-cp313-linux_x86_64.whl
+
+ENV ENABLE_TILE=1
+
 # Helion
 RUN sudo uv pip install --system helion