feat(frank-large): unsloth llama.cpp Qwen3.8-Flash-Next UD-IQ4_XS (200k/1 slot, MTP depth 2)

Replace the CIRU v4.4.1 Orca runtime with the unsloth llama.cpp prebuilt
(b11030-mix-5ff778e, ROCm gfx1151, bundles its own ROCm) serving
unsloth/Qwen3.8-Flash-Next-GGUF:UD-IQ4_XS (87.3 GiB, three HF split parts
concatenated) on the Strix Halo iGPU. One conversation, 200,000 ctx,
PARALLEL_SLOTS=1, MTP depth 2 via the explicit -md shared-Q8_0 head
(sidecar auto-discovery does not search the mtp/ subfolder), text-only.
Fleet contract unchanged: port 7770, alias frank-large.

- serve-frank-large.sh: unsloth binary, -m/-md, --spec-type draft-mtp
  --spec-draft-n-max 2, --jinja, preserve_thinking; gates on binary,
  GGUF, MTP head; conditional --mmproj on ENABLE_VISION=1
- download-frank-large-unsloth.sh: resumable fetch of 3 parts + MTP head
  + mmproj, each verified against its LFS sha256 fetched live from the
  Hub tree API; concatenates parts, records/verifies SHA256SUMS
- deploy-remote.sh: LLM_LARGE_MODEL/LLM_LARGE_DRAFT paths, pkill pattern
  on the model path (not the binary name), wait_port_free gate
- tests: seams for 200k/1-slot, explicit -md, text-only, handler gates,
  sweep safety

scripts/frank-large.service

@@ -1,5 +1,5 @@
 [Unit]
-Description=CIRU v4.4.1 Orca Qwen3.8-Flash (dankclaw, frank-large, Strix Halo iGPU gfx1151)
+Description=unsloth llama.cpp (b11030, ROCm gfx1151) Qwen3.8-Flash-Next UD-IQ4_XS (dankclaw, frank-large, Strix Halo iGPU)
 After=network-online.target
 Wants=network-online.target