Tidy reasampler_processor.h ceiling, restamp contour publish, tighten pitch-shift test bound

Splits BuiltCapture/sourceRateRefusalText into processor_snapshot.h; fixes stale lock-nesting notes; restamp now also publishes liveContours_ like reload; tightens a slack test bound and one drifted comment.

tests/test_pitch_shift.cpp

@@ -1092,7 +1092,8 @@ static void testCadenceCornerIsUnmovedByAPitchSynchronousSplice() {
         std::printf("  [cadence corner, PSOLA] period %.0f (want %.0f, metric floor %.2f%%): "
                     "excess %.2f%% -> %.2f%%\n", period, want, floor, pctOff - floor,
                     pctOn - floor);
-        CHECK(pctOn - floor < 1.0);            // the corner's real excess, PSOLA or not
+        CHECK(pctOff - floor < 0.1);            // the corner's real excess, PSOLA or not
+        CHECK(pctOn - floor < 0.1);             // measured 0.00% either way
         CHECK(pctOn < pctOff + 0.05);          // and PSOLA costs it nothing
     }
 }