feat: Introduce TimingManager for Accurate Frame Timing

- Added TimingManager class to provide precise timing for animations and frame pacing, addressing issues with ImGui::GetIO().DeltaTime.
- Updated event handling in the window management to use SDL_PollEvent for improved responsiveness.
- Integrated TimingManager into EditorManager, BackgroundRenderer, and WelcomeScreen for consistent delta time usage across the application.
- Enhanced animation updates to utilize accurate frame timing, improving visual performance and user experience.

src/app/editor/ui/background_renderer.cc

@@ -3,6 +3,7 @@
 #include <algorithm>
 #include <cmath>
 
+#include "app/core/timing.h"
 #include "app/gui/theme_manager.h"
 #include "imgui/imgui.h"
 
@@ -23,7 +24,7 @@ void BackgroundRenderer::RenderDockingBackground(ImDrawList* draw_list, const Im
                                                const ImVec2& window_size, const Color& theme_color) {
   if (!draw_list) return;
   
-  UpdateAnimation(ImGui::GetIO().DeltaTime);
+  UpdateAnimation(core::TimingManager::Get().GetDeltaTime());
   
   // Get current theme colors
   auto& theme_manager = ThemeManager::Get();