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.

src/core/instrument/engine/pitch_shift.h

@@ -60,7 +60,7 @@ struct SpliceEvent {
     std::int64_t jump = 0;     // the clamped nominal jump actually applied (signed)
     std::int64_t lag = 0;      // correlation best integer lag
     double frac = 0.0;         // parabolic sub-sample refinement, [-0.5, 0.5]
-    std::int64_t fadeLen = 0;  // live (ratio-scaled) crossfade length chosen
+    std::int64_t fadeLen = 0;  // live crossfade length chosen (drift-scaled, either direction)
 };
 
 // The nominal splice jump for a source whose period is known: the multiple of `periodFrames`