feat(semif): 0.1.3 — order averaging, fast kernels, bug-hunt hardening (Prime)

Order averaging (Prime, after the 739aa03 spike):
- A decision may set orderings: rotations|all (all only for <= 4 options). Every
  ordering goes to the engine in one shared batch.
- The reply keeps each native result and adds combined {probabilities (log-mean),
  top, agreement, spread}.
- Through the service on SemIf's labelled sets (252 rows): 78.6% -> 88.1%
  (group-bootstrap 95% CI +5.1..+14.3). Unanimous agreement is 94.5% accurate.

Fast kernels: flash-linear-attention 0.5.2 and causal-conv1d 1.7.0 are now the
default build. A/B on the empty GPU 3:
- parity with upstream went from 142/144 to 144/144;
- a ~2k-token /decide went from 169 to 92 ms server-side;
- short 3-rotation batches cost ~3-6 ms more.
triton builds a C shim at runtime, so the image carries gcc. Without it the
warm-up failed and startup failed closed.

Heid bug-hunt panel (4/4 arms, thread 01M3H3F4RR7XBP90KQ3A39H4SX), folded:
- Startup validation: VRAM cap 0 no longer means uncapped (C1); limits must be
  >= 1 (S1); the token must be visible ASCII (S2); the calibration file must
  exist and parse, with T in [0.05, 20] (S8, and C3's NaN leg).
- The body limit is checked before a chunk is kept, and a Unicode-digit
  Content-Length no longer crashes (C2, S3).
- Failures while building the response now get the 500 envelope (C3).
- 429 busy past SEMIF_MAX_QUEUE requests in progress (C6).
- The engine releases memory on every non-validation failure, unchained after
  gc; an empty OOM message is handled; 'out of memory' RuntimeErrors map to 503
  (C4, C5, S9).
- The entry point forces HF_HUB_OFFLINE (S10). README wording fixed (S5, S6).
- New guard tests close the gaps the arms' mutation grids exposed: early stop of
  the body read, a shared-route lock, calibration pass-through, the gc cycle,
  the exact caps, TorchEngine.load's arch and device checks, and the offline
  entry point.
86 tests.

Deployed on fv-ml1 GPU 1: parity 144/144, OOM and burst release verified, shared
capacity 63/51/26/16 rows at ~140/520/1960/3900 prefix tokens.

stacks/semif/compose.yaml

@@ -30,6 +30,8 @@ services:
       SEMIF_VRAM_CAP_GIB: ${VRAM_CAP_GIB:?set VRAM_CAP_GIB}
       SEMIF_MAX_TOKENS: ${MAX_TOKENS:-4096}
       SEMIF_MAX_DECISIONS: ${MAX_DECISIONS:-64}
+      # POSTs in progress (queued + scoring) before new ones get 429 busy.
+      SEMIF_MAX_QUEUE: ${MAX_QUEUE:-32}
       SEMIF_CALIBRATION: /conf/calibration.json
     volumes:
       # Pinned weights, read offline (HF_HUB_OFFLINE=1 in the image). Never downloads.