Move the speech-SNR floor from the timing gate to the pitch estimate

[logannye]

Three measured sessions reported zero voice segments and withheld all seven
voice metrics. The cause is arithmetic, not luck.

The measurement

eligibleSegments ends a segment on any unusable frame, and 32% of
speech-active frames sat below the 15 dB SNR floor, scattered through:

speech frames failing SNR      32%
expected contiguous usable run  3.1 frames = 31 ms
segment minimum                 2000 ms = 200 frames
P(a segment surviving)          1.5e-34

Zero segments was certain, in every session, before anyone spoke.

The floor was also in the wrong place

It exists so f0 is not estimated from speech buried in noise — a pitch
concern. Timing metrics need only reliable voice-activity detection, which is
robust well below 15 dB, and a noisy speech frame is still evidence that speech
occurred.

validPitch did not check SNR at all. So the gate was applied only where it did
harm and was absent where it belonged. It now lives in validPitch.

This is the same defect the face lane had twice: a gate built for one
measurement class applied to all of them. There it cost every bin; here it cost
every segment.

Tests

Drive 32%, 50%, and 95% of speech frames below the floor:

• timing measures through the first
• pitched duration falls at the second
• pitch withholds entirely at the third

The floor is relocated, not abandoned.

Contract

Pack 3.2.0 → 3.3.0, voice algorithm versions to 1.1.0. Voice
measurements are not interchangeable across this bump. The registry/pack parity
test caught the version mismatch before it shipped.

Deliberately not changed

The face lane. Its remaining failures are genuine head movement rather than
a structural gate, and the resting-pose fix has not yet been exercised on a real
session. Changing more before that data arrives would be guessing — the same
mistake the corrected acceptance curve already made once in this project.

Verification

277 unit tests, typecheck, structure + digest check, build, 6 browser e2e.

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