frank-primary: pin the -ot override set to the real tensor names

Discovery, not guesswork: dump the GGUF v3 headers of the fetched parts
(scripts/dump-gguf.py, added — a dependency-free reader that never
touches tensor data, so a 50 GiB part scans in milliseconds) before
the first load.

What the dump says (parts 2-3, 2026-09-26):

- The 51B-param PLE n-gram table is ONE tensor: per_layer_token_embd.
  weight, dims [160, 320001536], Q8_0, 54.4 GiB — exactly the whole of
  part 3. It is the same tensor the shared MTP head borrows, so the
  =CPU override is required for placement AND for the draft load
  (GPU-resident borrow: "invalid vector subscript").
- The model is qwen4exp, 512 experts, top-10 routing
  (qwen4exp.ple.ngram_size=3, heads_per_ngram=8).
- Part 1 is metadata-only (ntensors=0); parts 2-6 carry tensors.

The placeholder pattern ngram_embeddings matched nothing — dropped from
OT_OVERRIDES (env, serve-script default, seam, AGENTS.md, runbook,
LLM index) before it could masquerade as a working override at load
time. Deployed set: exps=CPU,per_layer_token_embd.weight=CPU.

Suite: 346 green.

scripts/serve-frank-primary.sh

@@ -50,7 +50,7 @@ fi
 : "${PARALLEL_SLOTS:=1}"
 : "${SPEC_DRAFT_N_MAX:=2}"
 : "${NGL:=999}"
-: "${OT_OVERRIDES:=exps=CPU,ngram_embeddings=CPU,per_layer_token_embd.weight=CPU}"
+: "${OT_OVERRIDES:=exps=CPU,per_layer_token_embd.weight=CPU}"
 : "${TENSOR_SPLIT:=1,1}"
 : "${SPEC_DRAFT_DEVICE:=ROCm0}"
 : "${BATCH_SIZE:=8192}"