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, 68 insertions, 0 deletions

diff --git a/rust/crates/commands/src/history.rs b/rust/crates/commands/src/history.rs
new file mode 100644
index 00000000..f8792373
--- /dev/null
+++ b/rust/crates/commands/src/history.rs
@@ -0,0 +1,68 @@
+use scene::Project;
+
+use crate::command::{Command, CommandError, CommandResult};
+
+#[derive(Default)]
+pub struct CommandHistory {
+    history: Vec<Box<dyn Command>>,
+    redo_stack: Vec<Box<dyn Command>>,
+}
+
+impl CommandHistory {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn execute(
+        &mut self,
+        mut command: Box<dyn Command>,
+        project: &mut Project,
+    ) -> Result<Option<CommandResult>, CommandError> {
+        let result = command.execute(project)?;
+        self.history.push(command);
+        self.redo_stack.clear();
+        Ok(result)
+    }
+
+    pub fn push(&mut self, command: Box<dyn Command>) {
+        self.history.push(command);
+        self.redo_stack.clear();
+    }
+
+    pub fn undo(&mut self, project: &mut Project) {
+        let Some(mut command) = self.history.pop() else {
+            return;
+        };
+        command.undo(project);
+        self.redo_stack.push(command);
+    }
+
+    pub fn redo(
+        &mut self,
+        project: &mut Project,
+    ) -> Result<Option<CommandResult>, CommandError> {
+        let Some(mut command) = self.redo_stack.pop() else {
+            return Ok(None);
+        };
+        let result = command.redo(project)?;
+        self.history.push(command);
+        Ok(result)
+    }
+
+    pub fn can_undo(&self) -> bool {
+        !self.history.is_empty()
+    }
+
+    pub fn can_redo(&self) -> bool {
+        !self.redo_stack.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.history.len()
+    }
+
+    pub fn clear(&mut self) {
+        self.history.clear();
+        self.redo_stack.clear();
+    }
+}