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.

apps/web/src/hooks/timeline/element/use-element-resize.ts

@@ -86,12 +86,8 @@ export function useTimelineElementResize({
 	};
 
 	const canExtendElementDuration = useCallback(() => {
-		if (element.type === "text" || element.type === "image") {
-			return true;
-		}
-
-		return false;
-	}, [element.type]);
+		return element.sourceDuration == null;
+	}, [element.sourceDuration]);
 
 	const updateTrimFromMouseMove = useCallback(
 		({ clientX }: { clientX: number }) => {