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, 113 insertions, 0 deletions

diff --git a/rust/crates/scene/src/factory.rs b/rust/crates/scene/src/factory.rs
new file mode 100644
index 00000000..d9a8e8a0
--- /dev/null
+++ b/rust/crates/scene/src/factory.rs
@@ -0,0 +1,113 @@
+use chrono::{DateTime, TimeZone, Utc};
+use time::{FrameRate, MediaTime};
+use uuid::Uuid;
+
+use crate::project::{
+    Background, CanvasSize, CanvasSizeMode, Project, ProjectMetadata, ProjectSettings,
+};
+use crate::scene::Scene;
+use crate::track::{SceneTracks, Track};
+
+pub const MAIN_TRACK_NAME: &str = "Main Track";
+pub const CURRENT_PROJECT_VERSION: u32 = 32;
+pub const DEFAULT_BACKGROUND_COLOR: &str = "#000000";
+pub const DEFAULT_CANVAS_SIZE: CanvasSize = CanvasSize {
+    width: 1920,
+    height: 1080,
+};
+pub const DEFAULT_FPS: FrameRate = FrameRate {
+    numerator: 30,
+    denominator: 1,
+};
+
+pub fn generate_id() -> String {
+    Uuid::new_v4().to_string()
+}
+
+fn now_millis() -> DateTime<Utc> {
+    Utc.timestamp_millis_opt(Utc::now().timestamp_millis()).unwrap()
+}
+
+pub fn build_default_scene(name: impl Into<String>, is_main: bool) -> Scene {
+    let now = now_millis();
+    Scene {
+        id: generate_id(),
+        name: name.into(),
+        is_main,
+        tracks: SceneTracks {
+            overlay: Vec::new(),
+            main: Track::Video {
+                id: generate_id(),
+                name: MAIN_TRACK_NAME.to_string(),
+                elements: Vec::new(),
+                muted: false,
+                hidden: false,
+            },
+            audio: Vec::new(),
+        },
+        bookmarks: Vec::new(),
+        created_at: now,
+        updated_at: now,
+    }
+}
+
+pub fn new_project(name: impl Into<String>) -> Project {
+    let main_scene = build_default_scene("Main scene", true);
+    let now = now_millis();
+    Project {
+        metadata: ProjectMetadata {
+            id: generate_id(),
+            name: name.into(),
+            thumbnail: None,
+            duration: MediaTime::ZERO,
+            created_at: now,
+            updated_at: now,
+        },
+        current_scene_id: main_scene.id.clone(),
+        scenes: vec![main_scene],
+        settings: ProjectSettings {
+            fps: DEFAULT_FPS,
+            canvas_size: DEFAULT_CANVAS_SIZE,
+            canvas_size_mode: Some(CanvasSizeMode::Preset),
+            last_custom_canvas_size: None,
+            original_canvas_size: None,
+            background: Background::Color {
+                color: DEFAULT_BACKGROUND_COLOR.to_string(),
+            },
+        },
+        version: CURRENT_PROJECT_VERSION,
+        timeline_view_state: None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn new_project_matches_web_defaults() {
+        let project = new_project("Untitled Project");
+        assert_eq!(project.version, 32);
+        assert_eq!(project.scenes.len(), 1);
+        assert!(project.scenes[0].is_main);
+        assert_eq!(project.current_scene_id, project.scenes[0].id);
+        assert_eq!(project.settings.canvas_size.width, 1920);
+        assert_eq!(project.settings.fps.numerator, 30);
+        match &project.scenes[0].tracks.main {
+            Track::Video { name, .. } => assert_eq!(name, "Main Track"),
+            _ => panic!("main track must be video"),
+        }
+        match &project.settings.background {
+            Background::Color { color } => assert_eq!(color, "#000000"),
+            _ => panic!("default background must be color"),
+        }
+    }
+
+    #[test]
+    fn new_project_round_trips_through_json() {
+        let project = new_project("Test");
+        let json = serde_json::to_value(&project).unwrap();
+        let parsed: Project = serde_json::from_value(json).unwrap();
+        assert_eq!(parsed, project);
+    }
+}