chore: sync from fn-registry agent

CMakeLists.txt

@@ -0,0 +1,22 @@
+add_imgui_app(chart_demo
+    main.cpp
+    ${CMAKE_SOURCE_DIR}/functions/viz/line_plot.cpp
+    ${CMAKE_SOURCE_DIR}/functions/viz/scatter_plot.cpp
+    ${CMAKE_SOURCE_DIR}/functions/viz/bar_chart.cpp
+    ${CMAKE_SOURCE_DIR}/functions/viz/heatmap.cpp
+    # fps_overlay vive en fn_framework
+)
+
+# --- E2E tests (opt-in via -DFN_BUILD_TESTS=ON) ---
+if(FN_BUILD_TESTS)
+    add_imgui_app(chart_demo_tests
+        main.cpp
+        tests/chart_demo_tests.cpp
+        ${CMAKE_SOURCE_DIR}/functions/viz/line_plot.cpp
+        ${CMAKE_SOURCE_DIR}/functions/viz/scatter_plot.cpp
+        ${CMAKE_SOURCE_DIR}/functions/viz/bar_chart.cpp
+        ${CMAKE_SOURCE_DIR}/functions/viz/heatmap.cpp
+    )
+    # Excludes int main() from main.cpp so the test target provides its own.
+    target_compile_definitions(chart_demo_tests PRIVATE FN_TEST_BUILD)
+endif()