Add MI355X details (#108)

* Add AMD February 2026 competition: mxfp4-mm, moe-mxfp4, mixed-mla

3 problems targeting MI355X from AMD-AIM/reference-kernels@20260209.
Also fixes eval.py regex to support underscored keys and booleans.

* Document known moe-mxfp4 non-determinism issue on MI355X

aiter's fused_moe kernel produces different results across calls with
identical inputs on gfx950, causing the reference submission to fail
correctness checks against itself.

* Update AMD problems with latest changes from AMD-AIM

- mixed-mla: Add tp (tensor parallel) parameter, variable num_heads,
  qseqlen=4 prefill cases, updated test/benchmark shapes
- moe-mxfp4: Updated benchmark shapes with TP=4/TP=8 variants,
  different batch sizes
- mxfp4-mm: Added m=32 benchmark, adjusted shape set

* Increase AMD problem timeouts to 30 minutes

aiter JIT compilation on first run can take 10+ minutes on MI355X,
causing test timeouts. Bump all timeouts to 1800s (30 min).

Author: Mark Saroufim

problems/amd_202602.yaml

@@ -0,0 +1,19 @@
+name: AMD Developer Challenge February 2026
+deadline: "2026-03-15 06:00"
+description: "AMD Developer Challenge: MXFP4 matrix multiplication, Mixture-of-Experts, and Multi-head Latent Attention optimized for MI355X."
+problems:
+  - directory: amd_202602/mxfp4-mm
+    name: amd-mxfp4-mm
+    deadline: "2026-03-15 06:00"
+    gpus:
+      - MI355X
+  - directory: amd_202602/moe-mxfp4
+    name: amd-moe-mxfp4
+    deadline: "2026-03-15 06:00"
+    gpus:
+      - MI355X
+  - directory: amd_202602/mixed-mla
+    name: amd-mixed-mla
+    deadline: "2026-03-15 06:00"
+    gpus:
+      - MI355X