feat: port domain crates to Rust (session 1 complete)

All green: cargo test --workspace (~300 tests, 0 failures).
- timeline (45): placement, resize/ripple, split, snap, retime,
  audio separation, scene helpers
- animation (73): bezier solver, channel sampling, keyframe ops,
  split/clamp/clone, param definitions
- commands (9): Command trait, BatchCommand, history, 19 concrete
  commands, freeze-frame port 1:1
- audio (22): audible collection, range mixing, mastering limiter,
  rms/peak buckets
- text (19): cosmic-text layout/measure/raster, backgrounds,
  decorations
- graphics (52): full CSS gradient parser, tiny-skia raster,
  4 shape definitions
- effect-defs (16): blur definition, registry, pass resolution
- mask-defs (19): all 9 mask renderers via tiny-skia
- renderer (6): node model + scene builder port
- desktop: GPUI projects screen wired to ProjectStore
- scene: factory (web defaults: v32, Main Track, 1920x1080, 30fps)

1 files changed, 123 insertions, 0 deletions

diff --git a/rust/crates/renderer/src/node.rs b/rust/crates/renderer/src/node.rs
new file mode 100644
index 00000000..f10c78f9
--- /dev/null
+++ b/rust/crates/renderer/src/node.rs
@@ -0,0 +1,123 @@
+use std::path::PathBuf;
+
+use compositor::BlendMode;
+use scene::{Effect, ElementAnimations, Mask, ParamValues, RetimeConfig, TextElement};
+use time::MediaTime;
+
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub struct Transform {
+    pub scale_x: f64,
+    pub scale_y: f64,
+    pub position_x: f64,
+    pub position_y: f64,
+    pub rotate: f64,
+}
+
+impl Transform {
+    pub fn identity() -> Self {
+        Self {
+            scale_x: 1.0,
+            scale_y: 1.0,
+            ..Default::default()
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum MediaType {
+    Video,
+    Image,
+    Audio,
+}
+
+#[derive(Clone, Debug)]
+pub struct MediaSource {
+    pub id: String,
+    pub media_type: MediaType,
+    pub path: PathBuf,
+}
+
+#[derive(Clone, Debug)]
+pub struct VisualParams {
+    pub duration: MediaTime,
+    pub time_offset: MediaTime,
+    pub trim_start: MediaTime,
+    pub trim_end: MediaTime,
+    pub retime: Option<RetimeConfig>,
+    pub transform: Transform,
+    pub animations: Option<ElementAnimations>,
+    pub opacity: f64,
+    pub blend_mode: Option<BlendMode>,
+    pub effects: Vec<Effect>,
+    pub masks: Vec<Mask>,
+}
+
+#[derive(Clone, Debug)]
+pub struct TextNodeParams {
+    pub element: TextElement,
+    pub transform: Transform,
+    pub opacity: f64,
+    pub blend_mode: Option<BlendMode>,
+    pub canvas_center_x: f64,
+    pub canvas_center_y: f64,
+    pub canvas_height: f64,
+    pub effects: Vec<Effect>,
+}
+
+#[derive(Clone, Debug)]
+pub struct GraphicNodeParams {
+    pub visual: VisualParams,
+    pub definition_id: String,
+    pub params: ParamValues,
+}
+
+#[derive(Clone, Debug)]
+pub struct BlurBackgroundParams {
+    pub media_id: String,
+    pub path: PathBuf,
+    pub media_type: MediaType,
+    pub duration: MediaTime,
+    pub time_offset: MediaTime,
+    pub trim_start: MediaTime,
+    pub trim_end: MediaTime,
+    pub retime: Option<RetimeConfig>,
+    pub blur_intensity: f64,
+}
+
+#[derive(Clone, Debug)]
+pub struct EffectLayerParams {
+    pub effect_type: String,
+    pub effect_params: ParamValues,
+    pub time_offset: MediaTime,
+    pub duration: MediaTime,
+}
+
+#[derive(Clone, Debug)]
+pub struct StickerNodeParams {
+    pub visual: VisualParams,
+    pub sticker_id: String,
+    pub intrinsic_width: Option<f64>,
+    pub intrinsic_height: Option<f64>,
+}
+
+#[derive(Clone, Debug)]
+pub enum Node {
+    Root { duration: MediaTime, children: Vec<Node> },
+    Color { color: String },
+    BlurBackground(BlurBackgroundParams),
+    EffectLayer(EffectLayerParams),
+    Video { visual: VisualParams, media_id: String, path: PathBuf },
+    Image { visual: VisualParams, path: PathBuf, max_source_size: Option<u32> },
+    Sticker(StickerNodeParams),
+    Graphic(GraphicNodeParams),
+    Text(TextNodeParams),
+}
+
+impl Node {
+    pub fn children(&self) -> &[Node] {
+        match self {
+            Node::Root { children, .. } => children,
+            _ => &[],
+        }
+    }
+}