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_processor.h

@@ -28,6 +28,7 @@
 #include "public.sdk/source/vst/vstsinglecomponenteffect.h"
 
 #include "reaper_bridge.h"
+#include "sample_map.h"     // PerformanceMap (the instrument's owned zoned keymap)
 #include "sampler_core.h"
 
 namespace reasampler::vst {
@@ -97,10 +98,18 @@ public:
     // editor borrows it (outlives the editor).
     ReaperBridge& bridge() { return bridge_; }
     // The current selection id (main/UI thread reads for the editor). Guarded by
-    // selectionMutex_ — never touched on the audio thread.
+    // selectionMutex_ — never touched on the audio thread. In Tier 1 the selection is the
+    // Tier-0 FALLBACK sample (played chromatically when the performance map is empty); the
+    // zoned map, when non-empty, supersedes it.
     std::string selectedSampleId();
     void setSelectedSampleId(const std::string& id);
 
+    // The performance map (Tier 1: the zoned keymap the instrument owns; D-B). Read/written
+    // by the editor on the UI thread; snapshotted under performanceMutex_. NEVER read on the
+    // audio thread — reloadFromBank bakes it into the LoadedInstrument's Keymap off-thread.
+    PerformanceMap performanceMap();
+    void setPerformanceMap(const PerformanceMap& map);
+
 private:
     ReaperBridge bridge_;
 
@@ -139,11 +148,17 @@ private:
     std::vector<GraveyardEntry> graveyard_;  // drained on reclaim + setActive(false) + terminate
     std::mutex reloadMutex_;  // serializes off-thread reloads + graveyard access
 
-    // The selected sample id (instance state). Off-thread only; a small mutex guards the
-    // string against a getState/editor race. NOT read on the audio thread.
+    // The selected sample id (Tier-0 fallback sample). Off-thread only; a small mutex
+    // guards the string against a getState/editor race. NOT read on the audio thread.
     std::mutex selectionMutex_;
     std::string selectedSampleId_;
 
+    // The performance map (Tier 1: the instrument's owned zoned keymap). Off-thread only;
+    // guarded against a getState/editor race. NOT read on the audio thread — reloadFromBank
+    // bakes it into the LoadedInstrument's Keymap under the reload lock.
+    std::mutex performanceMutex_;
+    PerformanceMap performanceMap_;
+
     // Latched from setupProcessing so setActive/reload can size against it. Read
     // off-thread only.
     double sampleRate_ = 44100.0;