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, 20 insertions, 0 deletions

diff --git a/apps/web/src/lib/animation/number-channel.ts b/apps/web/src/lib/animation/number-channel.ts
new file mode 100644
index 00000000..67166156
--- /dev/null
+++ b/apps/web/src/lib/animation/number-channel.ts
@@ -0,0 +1,20 @@
+import type {
+	AnimationPropertyPath,
+	ElementAnimations,
+	NumberAnimationChannel,
+} from "@/types/animation";
+
+export function getNumberChannelForPath({
+	animations,
+	propertyPath,
+}: {
+	animations: ElementAnimations | undefined;
+	propertyPath: AnimationPropertyPath;
+}): NumberAnimationChannel | undefined {
+	const channel = animations?.channels[propertyPath];
+	if (!channel || channel.valueKind !== "number") {
+		return undefined;
+	}
+
+	return channel;
+}