Initialize Project Sacrifice backlog and source baseline

app/src/main/java/com/projectsacrifice/game/GameMath.java

@@ -0,0 +1,29 @@
+package com.projectsacrifice.game;
+
+public final class GameMath {
+    private GameMath() {}
+
+    public static float clamp(float value, float min, float max) {
+        return Math.max(min, Math.min(max, value));
+    }
+
+    public static boolean intersects(
+            float ax, float ay, float aw, float ah,
+            float bx, float by, float bw, float bh
+    ) {
+        return ax < bx + bw && ax + aw > bx && ay < by + bh && ay + ah > by;
+    }
+
+    public static float pingPong(float elapsedSeconds, float periodSeconds) {
+        if (periodSeconds <= 0f) return 0f;
+        double phase = (elapsedSeconds % periodSeconds) / periodSeconds;
+        return (float) ((1d - Math.cos(phase * Math.PI * 2d)) * 0.5d);
+    }
+
+    public static String formatTime(long elapsedMs) {
+        long totalSeconds = Math.max(0L, elapsedMs) / 1000L;
+        long minutes = totalSeconds / 60L;
+        long seconds = totalSeconds % 60L;
+        return String.format(java.util.Locale.US, "%02d:%02d", minutes, seconds);
+    }
+}