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, 187 insertions, 0 deletions

diff --git a/rust/crates/scene/src/element.rs b/rust/crates/scene/src/element.rs
new file mode 100644
index 00000000..ef6980f8
--- /dev/null
+++ b/rust/crates/scene/src/element.rs
@@ -0,0 +1,187 @@
+use serde::{Deserialize, Serialize};
+use time::MediaTime;
+
+use crate::animation::ElementAnimations;
+use crate::effect::Effect;
+use crate::mask::Mask;
+use crate::params::ParamValues;
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct ElementRef {
+    pub track_id: String,
+    pub element_id: String,
+}
+
+#[derive(Serialize, Deserialize, Clone, Copy, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct RetimeConfig {
+    pub rate: f64,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub maintain_pitch: Option<bool>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct BaseTimelineElement {
+    pub id: String,
+    pub name: String,
+    pub duration: MediaTime,
+    pub start_time: MediaTime,
+    pub trim_start: MediaTime,
+    pub trim_end: MediaTime,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub source_duration: Option<MediaTime>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub animations: Option<ElementAnimations>,
+    #[serde(default)]
+    pub params: ParamValues,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct VideoElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    pub media_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub is_source_audio_enabled: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub hidden: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub retime: Option<RetimeConfig>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effects: Option<Vec<Effect>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub masks: Option<Vec<Mask>>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct ImageElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    pub media_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub hidden: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effects: Option<Vec<Effect>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub masks: Option<Vec<Mask>>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct TextElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub hidden: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effects: Option<Vec<Effect>>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct StickerElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    pub sticker_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub intrinsic_width: Option<f64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub intrinsic_height: Option<f64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub hidden: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effects: Option<Vec<Effect>>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct GraphicElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    pub definition_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub hidden: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub effects: Option<Vec<Effect>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub masks: Option<Vec<Mask>>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct EffectElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    pub effect_type: String,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct UploadAudioElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub retime: Option<RetimeConfig>,
+    pub media_id: String,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct LibraryAudioElement {
+    #[serde(flatten)]
+    pub base: BaseTimelineElement,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub retime: Option<RetimeConfig>,
+    pub source_url: String,
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(tag = "sourceType", rename_all = "camelCase")]
+pub enum AudioElement {
+    Upload(UploadAudioElement),
+    Library(LibraryAudioElement),
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
+#[serde(tag = "type", rename_all = "camelCase")]
+pub enum Element {
+    Audio(AudioElement),
+    Video(VideoElement),
+    Image(ImageElement),
+    Text(TextElement),
+    Sticker(StickerElement),
+    Graphic(GraphicElement),
+    Effect(EffectElement),
+}
+
+impl Element {
+    pub fn base(&self) -> &BaseTimelineElement {
+        match self {
+            Element::Audio(AudioElement::Upload(e)) => &e.base,
+            Element::Audio(AudioElement::Library(e)) => &e.base,
+            Element::Video(e) => &e.base,
+            Element::Image(e) => &e.base,
+            Element::Text(e) => &e.base,
+            Element::Sticker(e) => &e.base,
+            Element::Graphic(e) => &e.base,
+            Element::Effect(e) => &e.base,
+        }
+    }
+
+    pub fn base_mut(&mut self) -> &mut BaseTimelineElement {
+        match self {
+            Element::Audio(AudioElement::Upload(e)) => &mut e.base,
+            Element::Audio(AudioElement::Library(e)) => &mut e.base,
+            Element::Video(e) => &mut e.base,
+            Element::Image(e) => &mut e.base,
+            Element::Text(e) => &mut e.base,
+            Element::Sticker(e) => &mut e.base,
+            Element::Graphic(e) => &mut e.base,
+            Element::Effect(e) => &mut e.base,
+        }
+    }
+}