test(cpp): add text_editor_smoke build gate for issue 0025

App minima (no abre ventana ImGui) que crea/settea/lee text_editor y registra
un watch sobre /tmp/fn_smoke_test.txt para confirmar que TextEditor.cpp del
vendor + text_editor.cpp + file_watcher.cpp enlazan correctamente. Activada
por defecto si la carpeta existe (no requiere la primitives_gallery).

Tambien anade flag FN_BUILD_GALLERY (OFF default) para no romper el build
cuando la primitives_gallery no esta presente — sus deps (button.cpp,
toolbar.cpp...) son sources untracked en algunas branches.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cpp/CMakeLists.txt

@@ -115,6 +115,19 @@ if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/shaders_lab/CMakeLists.txt)
     add_subdirectory(apps/shaders_lab)
 endif()
 
+# --- Primitives Gallery ---
+# Activado solo si la app esta presente Y todos sus deps tambien (button, toolbar...
+# son sources untracked en este worktree). Forzar con FN_BUILD_GALLERY=ON.
+if(FN_BUILD_GALLERY AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/primitives_gallery/CMakeLists.txt)
+    add_subdirectory(apps/primitives_gallery)
+endif()
+
+# --- text_editor + file_watcher smoke test (issue 0025) ---
+# Build gate para validar que text_editor.cpp + file_watcher.cpp + vendor enlazan.
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/text_editor_smoke/CMakeLists.txt)
+    add_subdirectory(apps/text_editor_smoke)
+endif()
+
 # --- Registry Dashboard (lives in projects/fn_monitoring/apps/) ---
 set(_DASH_DIR ${CMAKE_SOURCE_DIR}/../projects/fn_monitoring/apps/registry_dashboard)
 if(EXISTS ${_DASH_DIR}/CMakeLists.txt)