feat: implement keyframe animation system

Add keyframe support for transform, opacity, and volume properties.
Includes animation engine (interpolation, mutations, resolvers), timeline
markers with selection/snapping, properties panel toggles, keyframe-aware
renderer, and full undo/redo command support.

Also refactor element command constructors to object params, extract
timeline pixel math to pixel-utils.ts, and update cursor rules.

1 files changed, 32 insertions, 6 deletions

diff --git a/apps/web/src/services/renderer/nodes/visual-node.ts b/apps/web/src/services/renderer/nodes/visual-node.ts
index 7179369e..50451b4a 100644
--- a/apps/web/src/services/renderer/nodes/visual-node.ts
+++ b/apps/web/src/services/renderer/nodes/visual-node.ts
@@ -2,8 +2,13 @@ import type { CanvasRenderer } from "../canvas-renderer";
 import { BaseNode } from "./base-node";
 import type { BlendMode } from "@/types/rendering";
 import type { Transform } from "@/types/timeline";
-
-const VISUAL_EPSILON = 1 / 1000;
+import type { ElementAnimations } from "@/types/animation";
+import {
+	getElementLocalTime,
+	resolveOpacityAtTime,
+	resolveTransformAtTime,
+} from "@/lib/animation";
+import { TIME_EPSILON_SECONDS } from "@/constants/animation-constants";
 
 export interface VisualNodeParams {
 	duration: number;
@@ -11,6 +16,7 @@ export interface VisualNodeParams {
 	trimStart: number;
 	trimEnd: number;
 	transform: Transform;
+	animations?: ElementAnimations;
 	opacity: number;
 	blendMode?: BlendMode;
 }
@@ -18,14 +24,22 @@ export interface VisualNodeParams {
 export abstract class VisualNode<
 	Params extends VisualNodeParams = VisualNodeParams,
 > extends BaseNode<Params> {
-	protected getLocalTime(time: number): number {
+	protected getSourceLocalTime(time: number): number {
 		return time - this.params.timeOffset + this.params.trimStart;
 	}
 
+	protected getAnimationLocalTime(time: number): number {
+		return getElementLocalTime({
+			timelineTime: time,
+			elementStartTime: this.params.timeOffset,
+			elementDuration: this.params.duration,
+		});
+	}
+
 	protected isInRange(time: number): boolean {
-		const localTime = this.getLocalTime(time);
+		const localTime = this.getSourceLocalTime(time);
 		return (
-			localTime >= this.params.trimStart - VISUAL_EPSILON &&
+			localTime >= this.params.trimStart - TIME_EPSILON_SECONDS &&
 			localTime < this.params.trimStart + this.params.duration
 		);
 	}
@@ -35,15 +49,27 @@ export abstract class VisualNode<
 		source,
 		sourceWidth,
 		sourceHeight,
+		timelineTime,
 	}: {
 		renderer: CanvasRenderer;
 		source: CanvasImageSource;
 		sourceWidth: number;
 		sourceHeight: number;
+		timelineTime: number;
 	}): void {
 		renderer.context.save();
 
-		const { transform, opacity } = this.params;
+		const animationLocalTime = this.getAnimationLocalTime(timelineTime);
+		const transform = resolveTransformAtTime({
+			baseTransform: this.params.transform,
+			animations: this.params.animations,
+			localTime: animationLocalTime,
+		});
+		const opacity = resolveOpacityAtTime({
+			baseOpacity: this.params.opacity,
+			animations: this.params.animations,
+			localTime: animationLocalTime,
+		});
 		const containScale = Math.min(
 			renderer.width / sourceWidth,
 			renderer.height / sourceHeight,