feat: introduce WebGL effects system and Blur effect

This implements the foundational architecture for video effects, starting with a multi-pass WebGL rendering pipeline and a customizable Gaussian Blur effect.

Key changes:
- WebGL Engine: Added `raw-loader` for `.glsl` shaders, multi-pass framebuffer rendering, and live offscreen canvas previews.
- Node Architecture: Replaced hardcoded background blur with `CompositeEffectNode` and added `EffectLayerNode` to apply effects to specific visual elements.
- Timeline & DND: Added a new `effect` track type. Upgraded drag-and-drop to support dropping effects directly onto the timeline. Consolidated track constants into a cleaner `TRACK_CONFIG`.
- UI/UX: Added an Effects tab in the assets panel with live previews. Added an Effect Properties panel with sliders and inputs for fine-tuning parameters.
- Data Model: Added `sourceDuration` to video and audio elements, and wrote a v8 storage migration to update existing projects to the new schema.
- Docs: Added `CHANGELOG.md` tracking v0.1.0 and v0.2.0, plus `docs/effects-renderer.md` to document the new WebGL pipeline.

1 files changed, 82 insertions, 0 deletions

diff --git a/apps/web/src/services/renderer/nodes/effect-layer-node.ts b/apps/web/src/services/renderer/nodes/effect-layer-node.ts
new file mode 100644
index 00000000..3d84be2b
--- /dev/null
+++ b/apps/web/src/services/renderer/nodes/effect-layer-node.ts
@@ -0,0 +1,82 @@
+import type { CanvasRenderer } from "../canvas-renderer";
+import { getEffect } from "@/lib/effects";
+import type { EffectParamValues } from "@/types/effects";
+import { BaseNode } from "./base-node";
+import { webglEffectRenderer } from "../webgl-effect-renderer";
+
+const TIME_EPSILON = 1e-6;
+
+export type EffectLayerNodeParams = {
+	effectType: string;
+	effectParams: EffectParamValues;
+	timeOffset: number;
+	duration: number;
+};
+
+function isInRange({
+	time,
+	timeOffset,
+	duration,
+}: {
+	time: number;
+	timeOffset: number;
+	duration: number;
+}): boolean {
+	return (
+		time >= timeOffset - TIME_EPSILON &&
+		time < timeOffset + duration + TIME_EPSILON
+	);
+}
+
+// snapshots whatever is currently on the canvas, applies the effect, draws it back
+export class EffectLayerNode extends BaseNode<EffectLayerNodeParams> {
+	async render({
+		renderer,
+		time,
+	}: {
+		renderer: CanvasRenderer;
+		time: number;
+	}): Promise<void> {
+		if (
+			!isInRange({
+				time,
+				timeOffset: this.params.timeOffset,
+				duration: this.params.duration,
+			})
+		) {
+			return;
+		}
+
+		const source = renderer.context.canvas as CanvasImageSource;
+
+		const effectDefinition = getEffect({
+			effectType: this.params.effectType,
+		});
+
+		const passes = effectDefinition.renderer.passes.map((pass) => ({
+			fragmentShader: pass.fragmentShader,
+			uniforms: pass.uniforms({
+				effectParams: this.params.effectParams,
+				width: renderer.width,
+				height: renderer.height,
+			}),
+		}));
+		const effectResult = webglEffectRenderer.applyEffect({
+			source,
+			width: renderer.width,
+			height: renderer.height,
+			passes,
+		});
+
+		renderer.context.save();
+		renderer.context.clearRect(0, 0, renderer.width, renderer.height);
+		renderer.context.drawImage(
+			effectResult,
+			0,
+			0,
+			renderer.width,
+			renderer.height,
+		);
+		renderer.context.restore();
+	}
+}