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, 12 insertions, 0 deletions

diff --git a/rust/crates/scene/src/params.rs b/rust/crates/scene/src/params.rs
new file mode 100644
index 00000000..e59c16b5
--- /dev/null
+++ b/rust/crates/scene/src/params.rs
@@ -0,0 +1,12 @@
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(untagged)]
+pub enum ParamValue {
+    Number(f64),
+    String(String),
+    Bool(bool),
+}
+
+pub type ParamValues = BTreeMap<String, ParamValue>;