feat: GPUI desktop port foundation

- scene crate: full project/scene/element model, serde round-trip
  proven against the web SerializedProject shape
- transfer crate: .ocp zip container, cross-compat with web fflate
  archives proven in both directions
- storage crate: filesystem project store replacing IndexedDB,
  .ocp import/export
- media crate: ffmpeg-next 8 decoder (frames, audio, thumbnails,
  waveform summaries)
- playback crate: wall-clock anchored, frame-rounded playback clock
- gpu crate: native texture readback; compositor renders headless
  offscreen on Vulkan (spike test)
- flake devshell: rust toolchain, GPUI native deps, ffmpeg dev,
  bindgen clang args; GPUI hello-world builds
- port plan in notes/gpui-port.md

1 files changed, 11 insertions, 0 deletions

diff --git a/rust/crates/timeline/src/creation.rs b/rust/crates/timeline/src/creation.rs
new file mode 100644
index 00000000..a399d3d7
--- /dev/null
+++ b/rust/crates/timeline/src/creation.rs
@@ -0,0 +1,11 @@
+use time::{MediaTime, TICKS_PER_SECOND};
+
+pub const DEFAULT_NEW_ELEMENT_DURATION: MediaTime =
+    MediaTime::from_ticks(5 * TICKS_PER_SECOND);
+
+pub fn to_element_duration_ticks(seconds: Option<f64>) -> Option<MediaTime> {
+    match seconds {
+        None => Some(DEFAULT_NEW_ELEMENT_DURATION),
+        Some(seconds) => MediaTime::from_seconds_f64(seconds),
+    }
+}