feat: impl IdlingRenderScheduler (#10547)

* feat: impl IdleRender

* test: pin time on Chromatic

* test: pin time on Chromatic

* fix: typo

* style: rename

* style: rename

* chore: back to setTimeout

* style: linebreak

* refactor: remove unused budget option

* refactor: use raw unix time

* fix: conflict error

* fix: floor

* fix: subtract

* Revert "fix: subtract"

This reverts commit 2ef4afaafc.

* Revert "fix: floor"

This reverts commit bef8ecdf45.

* Revert "refactor: use raw unix time"

This reverts commit 5199e13cb2.

packages/frontend/src/scripts/idle-render.ts

@@ -0,0 +1,38 @@
+class IdlingRenderScheduler {
+	#renderers: Set<FrameRequestCallback>;
+	#rafId: number;
+	#ricId: number;
+
+	constructor() {
+		this.#renderers = new Set();
+		this.#rafId = 0;
+		this.#ricId = requestIdleCallback((deadline) => this.#schedule(deadline));
+	}
+
+	#schedule(deadline: IdleDeadline): void {
+		if (deadline.timeRemaining()) {
+			this.#rafId = requestAnimationFrame((time) => {
+				for (const renderer of this.#renderers) {
+					renderer(time);
+				}
+			});
+		}
+		this.#ricId = requestIdleCallback((arg) => this.#schedule(arg));
+	}
+
+	add(renderer: FrameRequestCallback): void {
+		this.#renderers.add(renderer);
+	}
+
+	delete(renderer: FrameRequestCallback): void {
+		this.#renderers.delete(renderer);
+	}
+
+	dispose(): void {
+		this.#renderers.clear();
+		cancelAnimationFrame(this.#rafId);
+		cancelIdleCallback(this.#ricId);
+	}
+}
+
+export const defaultIdlingRenderScheduler = new IdlingRenderScheduler();