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, 25 insertions, 0 deletions

diff --git a/apps/web/src/lib/effects/definitions/blur.frag.glsl b/apps/web/src/lib/effects/definitions/blur.frag.glsl
new file mode 100644
index 00000000..2c015725
--- /dev/null
+++ b/apps/web/src/lib/effects/definitions/blur.frag.glsl
@@ -0,0 +1,25 @@
+precision mediump float;
+
+uniform sampler2D u_texture;
+uniform vec2 u_resolution;
+uniform float u_sigma;
+uniform vec2 u_direction;
+
+varying vec2 v_texCoord;
+
+void main() {
+  vec2 texelSize = 1.0 / u_resolution;
+
+  vec4 color = vec4(0.0);
+  float totalWeight = 0.0;
+
+  // step=1 texel — scaling step size instead causes discrete ghosting artifacts
+  for (int i = -30; i <= 30; i++) {
+    float fi = float(i);
+    float weight = exp(-(fi * fi) / (2.0 * u_sigma * u_sigma));
+    color += texture2D(u_texture, v_texCoord + texelSize * u_direction * fi) * weight;
+    totalWeight += weight;
+  }
+
+  gl_FragColor = color / totalWeight;
+}