fix(parakeet): move the seat from the empty GPU 3 to GPU 0

Placed on GPU 3 first because it was the empty card. That was the wrong read:
the seat is ~800 MiB, under 1% of a 96 GB card, so the question was never "where
does it fit" but "whose headroom is cheapest to spend".

vLLM sizes its KV cache as a fraction of TOTAL VRAM, not free VRAM. A resident
tenant on an otherwise-clean card therefore does not cost its own megabytes — it
costs the profiling margin of whatever full-size seat lands there later, and
flash-next needs 93 GiB of 96. A 96 GB card at 2 MiB can still take that; the
same card at 922 MiB is one where the next big seat needs its utilization
hand-trimmed, which this repo's flash-next history shows is both thin and silent
when it goes wrong.

Committed utilization per card is the number that governs, not free bytes:

    GPU 0   0.40 + 0.48                       = 0.88    ~13 GB spare  <- moved here
    GPU 1   0.52+0.24+0.10+0.055+0.03+0.03    = 0.975   ~4.3 GB
    GPU 2   0.96                                        ~1.8 GB
    GPU 3   -                                           kept empty as reserve

GPU 3 is back to 2 MiB / 97,247 MiB free and is now documented as a deliberate
reserve rather than a spare.

Post-move n=5 on the same clip: 0.68 / 0.54 / 0.54 / 0.52 / 0.53 s, median 0.54 s
against 0.50 s on GPU 3. The spreads overlap at this sample size and no difference
is claimed; the GPU 3 figure was taken on an idle card and is now noted as a best
case, since the seat shares GPU 0 with the hot serving path. Silence control and
the gateway round-trip both re-verified after the move.

Also records both Parakeet endpoints (FV v3 on Blackwell, IRV v2 on a 3090) and
the four confounds that make them not an A/B pair, sent to tts-dev for the bench.

persistent-memory.md

@@ -175,7 +175,7 @@ hardened for ha-dev (`d1769ed` ff); `kb` KB-search tool (`68fa80f`).
 
 ## Recent decisions
 
-- `[2026-09-15]` **Parakeet STT live on fv-ml1 GPU 3, behind LiteLLM `ext-stt` / `whisper-1`.** Retargeted the existing `stacks/parakeet/` (sherpa-onnx + our own FastAPI wrapper) from irv-ml1; v3 int8, 25 languages. ⚠ **ORT's CUDA EP compiles kernels lazily and the first decode on sm_120 took 45.7 s** — every later call ~0.5 s; a startup warmup in `app.py` now absorbs it, so the first real request is 0.65 s instead of a 45 s hang that no client would wait through. GPU use was **verified by a process on GPU 3 (922 MiB), not by the `provider=cuda` log line**, because ORT falls back to CPU silently and still returns correct text. Silence → `""` (null control), known sentence → near-exact (positive control). → `persistent-memory.d/2026-09-15-parakeet-stt-fv-ml1.md`
+- `[2026-09-15]` **Parakeet STT live on fv-ml1 GPU 0, behind LiteLLM `ext-stt` / `whisper-1`.** ⚠ **Placed on GPU 3 first, which was wrong — operator caught it.** A ~800 MiB seat should ride the card with the most uncommitted headroom (GPU 0, util 0.88, ~13 GB spare), not put the first fingerprint on the one pristine 96 GB card: vLLM sizes KV cache against TOTAL VRAM, so any tenant on an empty card eats a future full-size seat's profiling margin (flash-next needs 93 of 96 GiB). **GPU 3 is now a deliberate reserve at 2 MiB.** Retargeted the existing `stacks/parakeet/` (sherpa-onnx + our own FastAPI wrapper) from irv-ml1; v3 int8, 25 languages. ⚠ **ORT's CUDA EP compiles kernels lazily and the first decode on sm_120 took 45.7 s** — every later call ~0.5 s; a startup warmup in `app.py` now absorbs it, so the first real request is 0.65 s instead of a 45 s hang that no client would wait through. GPU use was **verified by a process on GPU 3 (922 MiB), not by the `provider=cuda` log line**, because ORT falls back to CPU silently and still returns correct text. Silence → `""` (null control), known sentence → near-exact (positive control). → `persistent-memory.d/2026-09-15-parakeet-stt-fv-ml1.md`
 
 - `[2026-09-15]` **`svos_miranda` Hermes plugin validated; found its load blocker.** Absolute intra-package imports (`from hermes_plugin.x`) could not resolve at the documented install name — fixed by svos-dev at `c964e64`. ⚠ **`hermes plugins validate` and `doctor` can NEVER pass this plugin**, by construction: validate's probe stub is config-blind AND returns `None` from `register_tool` (which the plugin's guard reads as a collision), and doctor runs under a temp `HERMES_HOME` with no config. ⚠ `doctor` exits **0** on ERROR (use `--ci`); `compat` reads a **nonexistent path as a pass**. Roster verified 8/7 by a probe supplying real settings. → `persistent-memory.d/2026-09-15-svos-miranda-plugin-validation.md`