chore(dankclaw): reclaim 510G of retired payloads; fix a stale fallback

The disk was at 93% with 137G free. Nine retired payloads are now moved
to ~/.AGENTTRASH/20260928-retired-models/ with a MANIFEST.md giving a
restore command per item — moved, not deleted, and nothing is freed until
the purge is approved. Every one maps to a runtime already retired in the
runbook index.

Only the .gguf was taken from Qwen3.8-27B-UD-Q8_K_XL/: the live
frank-large DFlash2 drafter lives in that directory and stays put. The
manifest warns against restoring the directory wholesale.

Kept: checkpoints/ (23G) — unreferenced by the repo, but ComfyUI is live
and its workflows were not searched, so it is not confirmed dead. Also
logs/, because x4e-run.log is a SPARSE file (3.3G apparent, 4K real) and
frees nothing.

The reference check caught a live bug: serve-frank-small.sh's fallback
MODEL_DIR still pointed at the retired GSQ-RCO payload frank-small served
on 2026-09-16/17. frank-small.env has always overridden it, so the drift
was invisible — but a missing or unreadable env file would have turned a
config problem into a "missing asset" naming a model that is no longer
there. Repointed at Gemma4-12B-QAT/, which the env file already sets.

Not taken, by request: podman images (279G reclaimable, 95%) and the
uv+pip caches (73G). Together 352G of regenerable garbage, larger than
what was reclaimed here.

The 29.3G payload rollback target went with the rest, so the payload-only
rollback is now a re-fetch first; the runbook and AGENTS.md say so.

AGENTS.md

@@ -372,11 +372,16 @@ and a token on the curl command line is world-readable) and
 Both take `--verify-only`.
 
 Runbook: `serverAppConfigs-docs/LLM/frank-large-gufo-qwen38-27b.md`.
-Rollback, two ways: **payload only** — repoint `MODEL_FILE` at
-`/home/dank/models/Qwen3.8-27B-UD-Q8_K_XL/Qwen3.8-27B-UD-Q8_K_XL.gguf`,
-intact on disk. **Engine** — [[frank-large-unsloth-qwen38-27b-q8xl]], the
-b11030 prebuilt at `/home/dank/GitPackages/unsloth-llama-b11030/`; the only
-way to get Qwen-Sharp back.
+Rollback, two ways: **payload only** — re-fetch with
+`scripts/download-frank-large.sh` and repoint `MODEL_FILE` at
+`/home/dank/models/Qwen3.8-27B-UD-Q8_K_XL/Qwen3.8-27B-UD-Q8_K_XL.gguf`; that
+29.3 GiB target was **reclaimed on 2026-09-28** (staged to
+`~/.AGENTTRASH/20260928-retired-models/`, restorable from there), so it is
+no longer a one-minute flip. **Engine** —
+[[frank-large-unsloth-qwen38-27b-q8xl]], the b11030 prebuilt at
+`/home/dank/GitPackages/unsloth-llama-b11030/`; the only way to get
+Qwen-Sharp back. The DFlash2 drafter was never reclaimed and still lives in
+`Qwen3.8-27B-UD-Q8_K_XL/`.
 
 ### frank-small — llama.cpp on the RTX 3090 (Dankclaw, ACTIVE)