fix(processor): close S-VIEW-4 previewVelocity persistence loop

Add previewVelocity_ member to ReaSamplerProcessor; populate it in
getState and restore it in setState so the field round-trips in the
plugin, not just in the pure unit test. Clamp 1..127 at the
deserialize read boundary in sample_map.cpp.

src/vst/reasampler_processor.h

@@ -250,6 +250,12 @@ private:
     // NOT read on the audio thread.
     std::int64_t lastSeenBankGeneration_ = -1;
 
+    // S-VIEW-4 preview-trigger velocity (MIDI 1..127). Persisted in component state (v6) so the
+    // user's chosen strike velocity survives a project save/reload. No concurrent writer before
+    // Wave 2 (no editor knob yet) — setState and getState are the sole accessors, both on the
+    // load/save thread (host-serialized). Default kPreviewVelocityDefault (64).
+    std::uint8_t previewVelocity_ = kPreviewVelocityDefault;
+
     // Latched from setupProcessing so setActive/reload can size against it. Read
     // off-thread only. 0.0 is explicitly invalid — setupProcessing sets the real host rate
     // before any audio, and reloadFromBank guards on it before use.