Add motion design skills pack

Installed via npx skills add iart-ai/motion-design-skills. Kept the
project's existing remotion-video skill unchanged.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E35uEC1pGu95tUpM4b815L

.agents/skills/after-effects/scripts/sequential-offset.jsx

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+/*
+ * sequential-offset.jsx
+ * Staggers the selected layers in time so each starts OFFSET_FRAMES after
+ * the previous one (a "domino" / cascade start), based on the first
+ * selected layer's start time.
+ *
+ * Usage: select layers in a comp, then File > Scripts > Run Script File...
+ * Edit OFFSET_FRAMES and ORDER below.
+ */
+
+(function sequentialOffset() {
+    var OFFSET_FRAMES = 2;       // frames between each layer's start
+    var ORDER_BY_SELECTION = true; // true = order of selection; false = by current startTime
+
+    var comp = app.project.activeItem;
+    if (!(comp && comp instanceof CompItem)) {
+        alert("Open a composition and select two or more layers first.");
+        return;
+    }
+
+    var sel = comp.selectedLayers;
+    if (sel.length < 2) {
+        alert("Select at least two layers.");
+        return;
+    }
+
+    var frameDur = comp.frameDuration;          // seconds per frame
+    var offsetSec = OFFSET_FRAMES * frameDur;
+
+    // Build the working order.
+    var layers = [];
+    for (var i = 0; i < sel.length; i++) layers.push(sel[i]);
+    if (!ORDER_BY_SELECTION) {
+        layers.sort(function (a, b) { return a.startTime - b.startTime; });
+    }
+
+    var base = layers[0].startTime;
+
+    app.beginUndoGroup("Sequential Offset");
+    try {
+        for (var j = 0; j < layers.length; j++) {
+            layers[j].startTime = base + (j * offsetSec);
+        }
+    } finally {
+        app.endUndoGroup();
+    }
+})();