fix(frank-large): verify exactly the fetched file set, not the whole Hub tree

The verification looped over every LFS file under UD-IQ4_XS/ and MTP/ in
the live Hub tree — the five MTP head variants we do not fetch (BF16,
Q4_K_M, Q8_0, shared-BF16, shared-Q4_K_M) printed MISSING, set ok=False,
and set -e killed the script silently between verification and assembly
after a 3-hour download. Verify exactly the FILES set instead (passed to
python as argv), and report NOT IN HUB TREE when an expected file has
vanished upstream. Also fix the layout comment: the transport parts live
in UD-IQ4_XS/, not parts/.

serverAppConfigs-docs/LLM/frank-large-unsloth-qwen38-flash-next.md

@@ -79,7 +79,7 @@ One root unit, one process, one published port:
   - `mtp/mtp-Qwen3.8-Flash-Next-shared-Q8_0.gguf` — MTP head (2.6 GiB)
   - `vision/mmproj-F16.gguf` — projector (904 MB, not loaded while
     `ENABLE_VISION=0`)
-  - `parts/` + `SHA256SUMS` — transport parts and the assembled digest
+  - `UD-IQ4_XS/` + `SHA256SUMS` — transport parts and the assembled digest
 - **Fetch**: `scripts/download-frank-large-unsloth.sh` — resumable
   (`curl -fL -C -`), each part verified against its **LFS sha256 fetched
   live from the Hub tree API** (not a file that could drift), then the