Pin the keyword models to one thread each and ship them (V-487)

The gate loaded and worked on workpc and took mavwaked from 68% of one core
to 335%. onnxruntime sizes its intra-op pool to every core and spins between
runs, which an always-on gate scoring three graphs twelve times a second
provokes for the whole day. One thread per session brings it to 81%, so the
keyword costs about 13% of a core, and each graph still finishes well inside
its 80ms.

The unit now passes the three -wake- flags and the models sit beside
silero_vad.onnx in ~/.local/share/maven/models. The threshold is left at the
binary's default so there is one place to change it.

docs/deployment.md

@@ -170,7 +170,19 @@ The device is `plughw:0,0` and not `hw:0,0`. The fifine offers 2 channels at
 44100 or 48000 and nothing else, and mavwaked asks arecord for 16kHz mono. Bare
 `hw` dies on "Channels count non available" before a frame is read.
 
-There is no wake word yet (V-487 stage two), so the loop runs open.
+The three `-wake-` flags require the keyword "Мэйвен" (V-487 stage two). Drop
+them and the loop runs open, which is what it did before. The threshold is the
+binary's default of 0.999 and is not passed. Over 65 minutes of held-out
+Russian speech it woke her 0.9 times an hour against 2.8 at 0.99. That cost one
+lost render out of 126 (`docs/evals/2026-08-09-wake-word.md`).
+
+The three sessions are pinned to one thread each. onnxruntime otherwise sizes
+its pool to every core and spins between runs, which took mavwaked from 68% of
+one core to 335%. With the cap it sits at 81%, so the gate costs about 13%.
+
+A keyword shorter than 1.32s can be heard too late to be used. The head scores
+1.28s of audio, and the VAD has closed the utterance by then.
+"Мэйвен, <request>" is unaffected. A bare "Мэйвен" is the case that fails.
 
 mavwaked connects at startup and holds the conn, so a nudge routed to voice
 reaches the speaker before he has said anything (V-671). It used to connect

docs/evals/2026-08-09-wake-word.md

@@ -94,6 +94,14 @@ the head the whole request to peak during. A bare "Мэйвен" with nothing af
 it is the case that fails. One fix would hold an ignored utterance for a grace
 period and ship it if the keyword lands late. It is not built.
 
+## What it costs the workstation
+
+Under systemd on workpc, mavwaked sat at 335% of a core with the gate on and
+68% with only silero. onnxruntime sizes its thread pool to every core and spins
+between runs, and this gate runs three graphs twelve times a second. Pinning
+all three sessions to one thread brought it to 81%, so the keyword costs about
+13% of one core. The three graphs each finish in well under 80ms that way.
+
 ## What was not measured
 
 No room recordings. Every negative above is a clean corpus clip. This gate