test: the noise probe reads a measurement's band and HF reject

Five measurements on the same spiked `sine`, asking for corners 0, 50, 0, 0, 50 on one
channel: two windows under the (channel, fc) key, which is what exercises it.

    measure pkpk bare      noise=10.0 hf=0.0  value=2.987692   the stimulus, impulses included
    measure pkpk hf        noise=10.0 hf=50.0 value=1.990075   the waveform: pass one is filtered
    measure period noband  noise=0.0  hf=0.0  value=0.021290   supposed to be WRONG -- the control
    measure period band    noise=25.0 hf=0.0  value=0.200000   the band alone
    measure period hf      noise=0.0  hf=50.0 value=0.200000   the reject alone
    measure windows=2                                          the corner is part of the key

`pkpk hf` is the reading that says the filter reached *pass one* and not only pass two; a
value near 3 means it did not. `period noband` is deliberately the defect the band exists to
fix, and a future reader who "fixes" it has removed the check.

The band leg asks for **25 %** rather than the 10 % default, and that is arithmetic rather
than a workaround: the band is a share of the *window's* peak-to-peak, which with the
impulses in it is about 3, so 10 % is a half-band of 0.3 -- less than the 0.5 an impulse
moves the signal by. `MeasureOptions::noise_pct`'s own rationale says 10 % holds to a 0.3
interferer, and this mock's is 0.5, so the default could not clear it. The default band is
what the `period noband` and `period hf` legs are about.

verification.md now says the noise and measurement probes must not share a run: both push
onto `app.measures` and the later one would read the earlier one's rows.

docs/claude/verification.md

@@ -546,3 +546,7 @@ it measures and waits 2.5 s for the ring to refill after that structural change.
 80 kB, past UDP's ~65507-byte payload, and the mock dies on its first `sendto` while the run still exits 0).
 
 The three lines and what each must read are in `probe-readings.md`.
+
+`UDPSCOPE_PROBE_NOISE_MS` and `UDPSCOPE_PROBE_MEASURE_MS` must **not** be scheduled in the same run: both push
+onto `app.measures`, and the later one would read the earlier one's rows as its own. The noise probe carries
+its own measurement legs (see `probe-readings.md`), so nothing is lost by keeping them apart.