docs(iommu): record the executed flip to iommu=pt and its measured cost of nothing

Window 01:24-01:35. Byte-identical A/B (rebuild proved it: same 1,287,656 B corpus,
same billed token counts 59,024 / 21,568): cold prefill 1,585.1 -> 1,616.0 t/s
(+2.0 %), warm 208,531 -> 214,131, needle hit/hit both boots. The 13-16 % that
justified amd_iommu=off since 2026-09-11 does not exist on this host; the decode
delta (-9.7 %) is instrument noise -- three repeats of one request on the same boot
gave 31.8/46.9/47.8 t/s.

NPU precondition restored: amdxdna bound 0000:c6:00.1 (driver 0.7.0, firmware
amdnpu/17f0_11/npu_7.sbin), group 26 identity, PASID width 10, /dev/accel/accel0
root:render with dank in render. No endpoint deployed, so frank-npu stays retired
-- only its rationale changes. Gates: 0 failed units, 32 groups (31 identity + the
SD reader's DMA quirk), iGPU c5:00.0 identity with ATS, dragoon ledger unchanged
(74.1 GiB, no clamp, listening at 39.8 s).

Deferred on purpose: the pp_dpm_fclk pin (changes iGPU timing for everyone, nothing
co-runs yet) and PerfOpt (7.0.0-38 has zero perfopt symbols, 26.04 caps at 7.0.0-38.38).
Re-keyed: decision record banner/front matter/verification/revert + new execution
section, frank-npu rationale, AGENTS key lesson, both index pages.

serverAppConfigs-docs/index.md

@@ -387,9 +387,9 @@ The LLM inference fleet on the two hosts. Full index:
   and rollback target (2026-09-15 → 09-16): ik_llama.cpp serving
   mradermacher/Qwen3.8-Flash-Next-Uncensored-i1-Q4_K_M on the RTX 3090 +
   Strix Halo hybrid — its measured envelope is why the fleet went back
-- [[dankclaw-iommu-translation-off]] — why Dankclaw boots with
-  `amd_iommu=off` since 2026-09-11 (13-16 % prefill), what it cost
-  (the NPU endpoint), and how to revert
+- [[dankclaw-iommu-translation-off]] — Dankclaw's IOMMU boot line: `iommu=pt`
+  since 2026-10-18 (measured cost of identity DMA: nothing — +2.0 % prefill), the
+  `amd_iommu=off` era it replaced, and the tracked file + installer that own it
 - [[kingjones-strix-rocmfp4]] — the PRIOR frank-dragoon runbook
   (2026-08-30 → 2026-09-11) and the rollback target:
   kingjones777/Qwen3.8-Flash-Next-ROCmFP4-STRIX-GGUF on the card's