feat(intern-decision): persist the triton autotune cache across recreates

The ~6.5-9 s first-call-per-bucket autotune lived in the container's writable
layer and died on every recreate. 0.1.3 creates /tmp/triton-cache in the image
owned by 10001 so the named volume intern-decision_triton-cache inherits a
writable mount point, and compose mounts it.

Bucket model PROVEN, not inferred: 2,048-token buckets, 16 up to 32,768. After
one warmed call per bucket, 12 random sizes across 8k-32k were all warm (worst
2.09 s); cold entries cost 6.5-9 s. Full cold warm-up 109 s; warm re-run 17 s.

scripts/intern-decision-warmup: one noul call per bucket, MAX_TOKENS from
/health, two-point live calibration of the tokenizer's linear token model (a
single probe overcorrects and the aim oscillates around the bucket edge),
per-bucket wall times, non-zero exit on a missed bucket. Run it after an IMAGE
CHANGE only; the volume carries ordinary recreates (measured: force-recreate,
then a warmed 32k call answered in 2.11 s).

Acceptance on 0.1.3: JevBench 202/231, hard 83/111, 0 diffs / 924; warm 32k GPU
1 peak 15,218 MiB (budget 15,220; a COLD autotune touched 15,224 once, README
caveat); /decide answers. Artifacts in the acceptance dir.

services/intern-decision-serve/Dockerfile

@@ -39,6 +39,9 @@ RUN uv sync --frozen --no-dev $EXTRAS --no-editable --no-cache
 RUN groupadd --system --gid 10001 intern \
     && useradd --system --uid 10001 --gid 10001 --no-create-home --shell /usr/sbin/nologin intern
 USER intern
+# The mount point for the Triton autotune cache volume, created HERE so a fresh named volume
+# inherits intern:intern (a root-owned mount point would make every autotune write fail).
+RUN mkdir -p /tmp/triton-cache
 ENV PATH=/app/.venv/bin:$PATH \
     HF_HOME=/hf \
     HF_HUB_OFFLINE=1 \