feat(kotlin-compose): design system + 33 components + gallery_kt + e2e android emulator + scaffolder fixes

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

cpp/functions/gamedev/input_unified.h

@@ -0,0 +1,45 @@
+#pragma once
+
+// input_unified — frame-based unified input snapshot for SDL3.
+// Issue 0072b. Keyboard + mouse + gamepad + touch mapped to logical buttons.
+
+#include <SDL3/SDL.h>
+
+namespace fn::input {
+
+struct InputState {
+    // Logical buttons (any source mapped here).
+    bool left = false, right = false, up = false, down = false;
+    bool action_a = false, action_b = false, action_x = false, action_y = false;
+    bool start = false, back = false;
+
+    // Same buttons but "just pressed this frame" (rising edge).
+    bool left_pressed = false, right_pressed = false, up_pressed = false, down_pressed = false;
+    bool a_pressed = false, b_pressed = false, x_pressed = false, y_pressed = false;
+    bool start_pressed = false, back_pressed = false;
+
+    // Analog sticks [-1, 1].
+    float lx = 0.0f, ly = 0.0f, rx = 0.0f, ry = 0.0f;
+
+    // Mouse (window coords, pixels).
+    float mx = 0.0f, my = 0.0f;
+    bool m_left = false, m_right = false;
+    bool m_left_pressed = false, m_right_pressed = false;
+
+    // Touch (mobile / WASM). x/y normalized [0, 1].
+    struct Touch {
+        float x = 0.0f, y = 0.0f;
+        bool pressed = false;
+        int id = -1;
+    };
+    Touch touches[8];
+    int touch_count = 0;
+};
+
+// Call once per frame BEFORE processing SDL events. Clears *_pressed edges.
+void input_begin_frame(InputState& s);
+
+// Call for each SDL_Event in PollEvent loop.
+void input_process_event(InputState& s, const SDL_Event* e);
+
+}  // namespace fn::input