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, 2 insertions, 6 deletions

diff --git a/rust/crates/timeline/src/placement/mod.rs b/rust/crates/timeline/src/placement/mod.rs
index 8ad5710e..4eb2660e 100644
--- a/rust/crates/timeline/src/placement/mod.rs
+++ b/rust/crates/timeline/src/placement/mod.rs
@@ -1,4 +1,4 @@
-use scene::{Element, SceneTracks, Track};
+use scene::{SceneTracks, Track};
 use time::MediaTime;
 
 use crate::types::{ElementType, TrackType};
@@ -21,7 +21,7 @@ pub use insert_index::{
 };
 pub use main_track::{MAIN_TRACK_NAME, enforce_main_track_start, get_earliest_main_track_element};
 pub use overlap::can_place_time_spans_on_track;
-pub use resolve::resolve_track_placement;
+pub use resolve::{ResolveTrackPlacementParams, resolve_track_placement};
 pub use track_factory::build_empty_track;
 
 #[derive(Clone, Debug, PartialEq)]
@@ -98,7 +98,3 @@ pub fn ordered_tracks(tracks: &SceneTracks) -> Vec<&Track> {
         .chain(tracks.audio.iter())
         .collect()
 }
-
-pub fn track_elements(track: &Track) -> &[Element] {
-    track.elements()
-}