S5 Tier-1: zoned keymap editor + performance-map playback/persistence

Zone editor in the IPlugView LICE surface, zoned resolution built off-thread into the
LoadedInstrument keymap with Tier-0 fallback, performance map in VST3 component state
with v1 back-compat. Pure resolve/build/serialize + geometry with CTest coverage.

src/vst/reasampler_editor.h

@@ -54,7 +54,8 @@ private:
 #ifdef _WIN32
     // Draw the current surface into the child window's DC via a LICE bitmap.
     void paint(HDC hdc);
-    // Route a client-space click: select the sample row under (x, y), if any.
+    // Route a client-space click: bank-sample pick (left list), zone edit (right panel),
+    // or the "Add Zone" button.
     void onClick(int x, int y);
 
     static LRESULT CALLBACK wndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
@@ -62,16 +63,28 @@ private:
     HWND childHwnd_ = nullptr;
 #endif
 
-    // Re-read the bank's sample list from the live bridge into `samples_`. Main/UI
-    // thread only (reads ext-state); called on attach and after a selection reload.
+    // Re-read the bank's sample list from the live bridge into `samples_`, and snapshot the
+    // instrument's performance map. Main/UI thread only (reads ext-state); called on attach
+    // and after any edit that reloads the instrument.
     void refreshSampleList();
 
+    // Push the edited performance map to the processor and rebuild the instrument OFF the
+    // audio thread. UI thread only. Centralizes the "commit an edit" path so every zone
+    // mutation reloads identically.
+    void commitMapAndReload();
+
     ReaSamplerProcessor* processor_ = nullptr;
     // The bank's samples, snapshotted for the current paint. Refreshed off the audio
     // thread; the paint just draws it.
     std::vector<SampleChoice> samples_;
-    // The currently-selected sample id, mirrored for the paint's highlight.
+    // The currently-selected sample id (Tier-0 fallback + the "sample to add" for a new
+    // zone), mirrored for the paint's highlight.
     std::string selectedId_;
+    // The instrument's performance map, snapshotted for edit + paint. Edits mutate this
+    // copy then commit it to the processor via commitMapAndReload.
+    PerformanceMap map_;
+    // The zone row currently highlighted (for the paint); -1 = none.
+    int selectedZone_ = -1;
 };
 
 }  // namespace reasampler::vst