feat(editor): height scale tool for terrain relief control

- Scale Heights: multiply all terrain heights by a factor (0.1x - 5.0x)
- >1.0 exaggerates relief (deeper valleys, taller peaks)
- <1.0 flattens terrain toward base height
- Re-stitches all chunk edges after scaling for seamless results
- Workflow: noise → smooth → scale → clamp for precise control

tools/editor/editor_ui.cpp

@@ -404,8 +404,15 @@ void EditorUI::renderBrushPanel(EditorApp& app) {
                 app.getTerrainEditor().clampHeights(clampMin, clampMax);
                 app.showToast("Heights clamped");
             }
+            ImGui::Separator();
+            static float hScale = 1.5f;
+            ImGui::SliderFloat("Height Scale", &hScale, 0.1f, 5.0f, "%.2f");
+            if (ImGui::Button("Scale Heights", ImVec2(-1, 0))) {
+                app.getTerrainEditor().scaleHeights(hScale);
+                app.showToast("Heights scaled");
+            }
             ImGui::TextColored(ImVec4(0.6f, 0.6f, 0.6f, 1),
-                "Generate, smooth, then clamp for controlled range");
+                "Exaggerate (>1) or flatten (<1) terrain relief");
         }
 
         ImGui::Separator();

tools/editor/terrain_editor.cpp

@@ -652,6 +652,20 @@ void TerrainEditor::smoothEntireTile(int iterations) {
     dirty_ = true;
 }
 
+void TerrainEditor::scaleHeights(float factor) {
+    if (!terrain_) return;
+    for (int ci = 0; ci < 256; ci++) {
+        auto& chunk = terrain_->chunks[ci];
+        if (!chunk.hasHeightMap()) continue;
+        for (int v = 0; v < 145; v++)
+            chunk.heightMap.heights[v] *= factor;
+        dirtyChunks_.push_back(ci);
+    }
+    // Re-stitch all edges after scaling
+    for (int ci = 0; ci < 256; ci++) stitchEdges(ci);
+    dirty_ = true;
+}
+
 void TerrainEditor::clampHeights(float minH, float maxH) {
     if (!terrain_) return;
     for (int ci = 0; ci < 256; ci++) {

tools/editor/terrain_editor.hpp

@@ -60,6 +60,9 @@ public:
     // Clamp all heights to a min/max range
     void clampHeights(float minH, float maxH);
 
+    // Scale all heights by a factor (useful for exaggerating or flattening)
+    void scaleHeights(float factor);
+
     // Import/export heightmap (raw 16-bit grayscale, 129x129)
     bool importHeightmap(const std::string& path, float heightScale);
     bool exportHeightmap(const std::string& path, float heightScale);