Unify input behind Engine::Input facade; fix Ctrl+P and Pause button

New Engine/Core/Input.h/.cpp: static input facade with a Key/MouseButton
enum (values map to GLFW key codes internally) so scripts and game logic
no longer touch GLFW directly - window backend becomes swappable and the
facade is the surface to expose when embedding scripting later. Wired up
in Application's constructor; Camera (editor camera WASD/RMB/MMB), the
WASDMove script and SandboxApp key handling now query Input only.

Ctrl+P hotkey fix: the !m_Playing guard made the hotkey dead exactly
when it was needed - after pressing Play. Now toggles both ways.

Toolbar Pause button now reads "Resume" while paused (tooltip follows).

App/main.cpp

@@ -24,8 +24,8 @@
 #include <Engine/Renderer/Renderer.h>
 #include <Engine/Renderer/EditorCamera.h>
 
-#include <GLFW/glfw3.h>
-
+#include <Engine/Core/Input.h>
+
 #include "Editor.h"
 #include "EditorContext.h"
 
@@ -94,11 +94,12 @@ namespace
 
         void OnKeyPress(const Event& event) override
         {
-            if (event.key == GLFW_KEY_GRAVE_ACCENT)
+            // 键码统一走 Input::Key（App 层零 GLFW 依赖）
+            if (event.key == static_cast<int>(Input::Key::GraveAccent))
             {
                 SetImGuiEnabled(!GetImGuiEnabled());
             }
-            if (event.key == GLFW_KEY_F1)
+            if (event.key == static_cast<int>(Input::Key::F1))
             {
                 STATS.PrintComparison();
             }