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/editor_geometry.cpp

@@ -75,4 +75,90 @@ int sampleRowHitTest(const EditorLayout& layout, int rowCount, int x, int y) {
     return index;
 }
 
+// --- Keymap editor -----------------------------------------------------------
+
+KeymapEditorLayout layoutKeymapEditor(int w, int h) {
+    KeymapEditorLayout out;
+    out.base = layoutEditor(w, h);
+    const Rect& canvas = out.base.canvas;
+
+    // Split the canvas vertically: the left column is the bank-sample list, the right
+    // column (1/kZonePanelFraction of the width) is the zone panel. Guard tiny widths so
+    // the split point never crosses the canvas edges.
+    const int canvasW = std::max(0, canvas.width());
+    const int splitW = canvasW / kZonePanelFraction;          // width of the zone panel
+    const int splitX = std::max(canvas.left, canvas.right - splitW);
+
+    out.sampleList = Rect{canvas.left, canvas.top, splitX, canvas.bottom};
+    out.zonePanel = Rect{splitX, canvas.top, canvas.right, canvas.bottom};
+
+    // "Add Zone" button spans the top of the zone panel, clamped to its height.
+    const int addH = std::min(kAddZoneHeight, std::max(0, out.zonePanel.height()));
+    out.addZoneButton =
+        Rect{out.zonePanel.left, out.zonePanel.top, out.zonePanel.right,
+             out.zonePanel.top + addH};
+
+    // Zone rows stack below the button.
+    out.zoneRowArea = Rect{out.zonePanel.left, out.addZoneButton.bottom,
+                           out.zonePanel.right, out.zonePanel.bottom};
+    return out;
+}
+
+Rect keymapSampleRowRect(const KeymapEditorLayout& layout, int index) {
+    if (index < 0) return Rect{};
+    const int top = layout.sampleList.top + index * kSampleRowHeight;
+    return Rect{layout.sampleList.left, top, layout.sampleList.right,
+                top + kSampleRowHeight};
+}
+
+int keymapSampleRowHitTest(const KeymapEditorLayout& layout, int rowCount, int x, int y) {
+    if (rowCount <= 0) return -1;
+    const Rect& list = layout.sampleList;
+    if (x < list.left || x >= list.right) return -1;
+    if (y < list.top || y >= list.bottom) return -1;
+    const int index = (y - list.top) / kSampleRowHeight;
+    if (index < 0 || index >= rowCount) return -1;
+    const Rect r = keymapSampleRowRect(layout, index);
+    if (y >= r.bottom) return -1;
+    return index;
+}
+
+Rect zoneRowRect(const KeymapEditorLayout& layout, int index) {
+    if (index < 0) return Rect{};
+    const int top = layout.zoneRowArea.top + index * kZoneRowHeight;
+    return Rect{layout.zoneRowArea.left, top, layout.zoneRowArea.right,
+                top + kZoneRowHeight};
+}
+
+ZoneHit zoneHitTest(const KeymapEditorLayout& layout, int zoneCount, int x, int y) {
+    if (zoneCount <= 0) return ZoneHit{};
+    const Rect& area = layout.zoneRowArea;
+    if (x < area.left || x >= area.right) return ZoneHit{};
+    if (y < area.top || y >= area.bottom) return ZoneHit{};
+    const int index = (y - area.top) / kZoneRowHeight;
+    if (index < 0 || index >= zoneCount) return ZoneHit{};
+    const Rect row = zoneRowRect(layout, index);
+    if (y >= row.bottom) return ZoneHit{};
+
+    // Seven mini-buttons pinned to the right edge, right-to-left:
+    //   delete, root+, root-, high+, high-, low+, low-
+    // Each is kZoneCtrlWidth wide. A click left of the leftmost is the label ("select").
+    // The fields laid out LEFT-TO-RIGHT in slot order 0..6.
+    const ZoneField fields[7] = {
+        ZoneField::kLowDown, ZoneField::kLowUp,  ZoneField::kHighDown,
+        ZoneField::kHighUp,  ZoneField::kRootDown, ZoneField::kRootUp,
+        ZoneField::kDelete,
+    };
+    const int slots = 7;
+    const int ctrlBlockLeft = row.right - slots * kZoneCtrlWidth;
+    if (x < ctrlBlockLeft) return ZoneHit{index, ZoneField::kZoneNone};  // label -> select
+    const int slot = (x - ctrlBlockLeft) / kZoneCtrlWidth;
+    if (slot < 0 || slot >= slots) return ZoneHit{index, ZoneField::kZoneNone};
+    return ZoneHit{index, fields[slot]};
+}
+
+bool addZoneHitTest(const KeymapEditorLayout& layout, int x, int y) {
+    return contains(layout.addZoneButton, x, y);
+}
+
 }  // namespace reasampler::vst