feat: add multi-viewport support and SQLite amalgamation to C++ framework

- AppConfig.viewports flag para ventanas OS reales fuera del main window
- Multi-viewport render loop en app_base.cpp (UpdatePlatformWindows)
- SQLite amalgamation vendoreada para Windows cross-compile
- LANGUAGES C CXX en CMakeLists para compilar sqlite3.c
- Fix pie_chart.cpp para nueva API de ImPlot (PlotPieChart sin flags arg)
- imgui.ini añadido a gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cpp/framework/app_base.cpp

@@ -52,8 +52,20 @@ int run_app(AppConfig config, std::function<void()> render_fn) {
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
 
+    if (config.viewports) {
+        io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;
+    }
+
     ImGui::StyleColorsDark();
 
+    // When viewports are enabled, tweak WindowRounding/WindowBg so
+    // platform windows look consistent with the main window
+    if (config.viewports) {
+        ImGuiStyle& style = ImGui::GetStyle();
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL3_Init("#version 330");
 
@@ -80,6 +92,14 @@ int run_app(AppConfig config, std::function<void()> render_fn) {
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 
+        // Multi-viewport: update and render platform windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
+            GLFWwindow* backup_ctx = glfwGetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(backup_ctx);
+        }
+
         glfwSwapBuffers(window);
 
 #ifdef TRACY_ENABLE