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).

Engine/include/Engine/Core/Input.h

@@ -0,0 +1,89 @@
+//
+// Input.h：统一输入门面（脚本/游戏逻辑唯一入口）。
+//
+// 目的：
+//   1. 上层代码（脚本、SandboxApp、编辑器相机）不再直接依赖 GLFW——
+//      只依赖本枚举与门面，Window 后端将来可换（SDL/平台原生）
+//   2. 嵌入脚本时暴露的也是这一套（Lua/Python 绑定包一层即可）
+//
+// 键码值 = GLFW 物理键码（glf3.h 标准值），强转 int 可直接传给
+// Window::IsKeyPressed；但调用方不得依赖这一点。
+//
+// 语义：轮询接口沿用 Window 的门控规则——UI 捕获键盘（编辑器文本框
+// 输入中）时 IsKeyDown 返回 false，游戏侧静默；鼠标捕获同理。
+//
+
+#pragma once
+
+#include <glm/glm.hpp>
+
+namespace Engine {
+
+    class Window;
+
+    namespace Input {
+
+        enum class Key : int {
+            // ---- 可打印区（值 = ASCII）----
+            Space = 32,
+            Apostrophe = 39,
+            Comma = 44,
+            Minus = 45,
+            Period = 46,
+            Slash = 47,
+            Num0 = 48, Num1 = 49, Num2 = 50, Num3 = 51, Num4 = 52,
+            Num5 = 53, Num6 = 54, Num7 = 55, Num8 = 56, Num9 = 57,
+            Semicolon = 59,
+            Equal = 61,
+            A = 65, B = 66, C = 67, D = 68, E = 69, F = 70, G = 71,
+            H = 72, I = 73, J = 74, K = 75, L = 76, M = 77, N = 78,
+            O = 79, P = 80, Q = 81, R = 82, S = 83, T = 84, U = 85,
+            V = 86, W = 87, X = 88, Y = 89, Z = 90,
+            BracketLeft = 91,
+            Backslash = 92,
+            BracketRight = 93,
+            GraveAccent = 96,
+            // ---- 控制键（值 = GLFW 键码）----
+            Escape = 256,
+            Enter = 257,
+            Tab = 258,
+            Backspace = 259,
+            Insert = 260,
+            Delete = 261,
+            Right = 262,
+            Left = 263,
+            Down = 264,
+            Up = 265,
+            PageUp = 266,
+            PageDown = 267,
+            Home = 268,
+            End = 269,
+            F1 = 290, F2 = 291, F3 = 292, F4 = 293, F5 = 294, F6 = 295,
+            F7 = 296, F8 = 297, F9 = 298, F10 = 299, F11 = 300,
+            F12 = 301,
+            // ---- 修饰键 ----
+            LeftShift = 340,
+            LeftControl = 341,
+            LeftAlt = 342,
+            LeftSuper = 343,
+            RightShift = 344,
+            RightControl = 345,
+            RightAlt = 346,
+            RightSuper = 347,
+        };
+
+        enum class MouseButton : int {
+            Left = 0,    // GLFW_MOUSE_BUTTON_1
+            Right = 1,
+            Middle = 2,
+        };
+
+        // 装配：Application 构造时自动调用（后端 Window 就绪后）
+        void Init(const Window& window);
+
+        // 轮询查询（UI 捕获对应输入时返回 false——游戏侧静默）
+        bool IsKeyDown(Key key);
+        bool IsMouseButtonDown(MouseButton button);
+    }
+
+} // namespace Engine