feat(vst): S18 VST3 channel isolation — beta ReaSampler 9000 pairs with beta extension only

Fork the VST3 class UID (beta UID minted+frozen), on-disk name, and display
name by the one channel bit via app_version; couple UID selection to the
channel at compile time so a refactor can't split identity from data.

src/vst/reasampler_editor.cpp

@@ -18,7 +18,7 @@
 #include "peaks.h"             // computeEnvelope
 #include "reaper_bridge.h"
 #include "reasampler_processor.h"
-#include "reasampler_vst.h"    // kPluginName (the editor title band)
+#include "app_version.h"       // vstPluginName (channel-derived editor title band, S18)
 #include "sample_map.h"
 #include "wav_trim.h"          // parseWavLayout, extractFloatFrames
 #include "waveform_view.h"     // frame<->pixel markers + zero-crossing snap (S11)
@@ -477,7 +477,7 @@ void ReaSamplerEditor::paint(HDC hdc) {
     // Title band: product name + live readout.
     LICE_FillRect(&bmp, bands.title.left, bands.title.top, bands.title.width(),
                   bands.title.height(), kColTitleBg, 1.0f, 0);
-    std::string title = kPluginName;
+    std::string title = reasampler::vstPluginName();  // channel-derived (S18)
     if (processor_ && processor_->bridge().isConnected()) {
         if (samples_.empty()) title += "  [bank empty]";
         else if (selectedId_.empty() && map_.zones.empty()) title += "  [pick a capture]";