fix: remove scrollbar arrows from shapes + add collision slide-off

- Change inner div overflow from scroll to hidden, removing browser
  scrollbar arrows that appeared on every canvas shape
- Add shape collision detection: shapes now slide off each other with
  an 8px gap instead of overlapping when dragged (pointer + touch)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/folk-shape.ts

@@ -72,7 +72,7 @@ const styles = css`
 	div {
 		height: 100%;
 		width: 100%;
-		overflow: scroll;
+		overflow: hidden;
 		pointer-events: none;
 	}
 
@@ -249,6 +249,8 @@ export class FolkShape extends FolkElement {
 		this.requestUpdate("rotation");
 	}
 
+	static GAP = 8; // minimum gap between shapes
+
 	#highlighted = false;
 	get highlighted() {
 		return this.#highlighted;
@@ -348,6 +350,7 @@ export class FolkShape extends FolkElement {
 					// Apply movement
 					this.#rect.x += moveDelta.x;
 					this.#rect.y += moveDelta.y;
+					this.#resolveOverlaps(moveDelta.x, moveDelta.y);
 					this.requestUpdate();
 					this.#dispatchTransformEvent();
 				}
@@ -442,6 +445,7 @@ export class FolkShape extends FolkElement {
 			} else {
 				this.x += moveDelta.x;
 				this.y += moveDelta.y;
+				this.#resolveOverlaps(moveDelta.x, moveDelta.y);
 			}
 			event.preventDefault();
 			return;
@@ -603,6 +607,52 @@ export class FolkShape extends FolkElement {
 		this.requestUpdate();
 	}
 
+	/**
+	 * After moving, push this shape away from any overlapping siblings.
+	 * Uses the direction of the move to decide which side to slide to.
+	 */
+	#resolveOverlaps(dx: number, dy: number) {
+		const parent = this.parentElement;
+		if (!parent) return;
+
+		const gap = FolkShape.GAP;
+		const me = { x: this.x, y: this.y, w: this.width, h: this.height };
+
+		for (const sibling of parent.children) {
+			if (sibling === this || !(sibling instanceof FolkShape)) continue;
+			if (sibling.tagName.toLowerCase() === "folk-arrow") continue;
+
+			const other = { x: sibling.x, y: sibling.y, w: sibling.width, h: sibling.height };
+
+			// Check overlap (axis-aligned)
+			const overlapX = me.x < other.x + other.w + gap && me.x + me.w + gap > other.x;
+			const overlapY = me.y < other.y + other.h + gap && me.y + me.h + gap > other.y;
+
+			if (!overlapX || !overlapY) continue;
+
+			// Compute penetration depths from each side
+			const pushRight = (other.x + other.w + gap) - me.x;
+			const pushLeft  = me.x + me.w + gap - other.x;
+			const pushDown  = (other.y + other.h + gap) - me.y;
+			const pushUp    = me.y + me.h + gap - other.y;
+
+			// Pick the axis with the smallest penetration, biased by move direction
+			const minX = pushRight < pushLeft ? -pushRight : pushLeft;
+			const minY = pushDown < pushUp ? -pushDown : pushUp;
+
+			if (Math.abs(minX) < Math.abs(minY)) {
+				// Slide horizontally
+				this.#rect.x += dx <= 0 ? -pushLeft : pushRight;
+			} else {
+				// Slide vertically
+				this.#rect.y += dy <= 0 ? -pushUp : pushDown;
+			}
+
+			me.x = this.#rect.x;
+			me.y = this.#rect.y;
+		}
+	}
+
 	/**
 	 * Serialize shape to JSON for Automerge sync
 	 * Subclasses should override and call super.toJSON()