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, 12 insertions, 0 deletions

diff --git a/rust/crates/commands/src/timeline/element/mod.rs b/rust/crates/commands/src/timeline/element/mod.rs
index 2ba806e1..a1d8de6e 100644
--- a/rust/crates/commands/src/timeline/element/mod.rs
+++ b/rust/crates/commands/src/timeline/element/mod.rs
@@ -1,3 +1,15 @@
 pub mod delete_elements;
+pub mod duplicate_elements;
+pub mod insert_element;
+pub mod move_elements;
+pub mod shift_split_remainder;
+pub mod split_elements;
+pub mod update_elements;
 
 pub use delete_elements::DeleteElementsCommand;
+pub use duplicate_elements::DuplicateElementsCommand;
+pub use insert_element::{InsertElementCommand, InsertElementPlacement};
+pub use move_elements::{MoveElementCommand, PlannedElementMove, PlannedTrackCreation};
+pub use shift_split_remainder::ShiftSplitRemainderCommand;
+pub use split_elements::{RetainSide, SplitElementsCommand};
+pub use update_elements::{ElementUpdate, UpdateElementsCommand};