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, 94 insertions, 0 deletions

diff --git a/rust/crates/commands/src/bookmarks.rs b/rust/crates/commands/src/bookmarks.rs
new file mode 100644
index 00000000..79a73015
--- /dev/null
+++ b/rust/crates/commands/src/bookmarks.rs
@@ -0,0 +1,94 @@
+use scene::Bookmark;
+use time::{FrameRate, MediaTime};
+
+#[derive(Clone, Debug, Default, PartialEq)]
+pub struct BookmarkPatch {
+    pub note: Option<Option<String>>,
+    pub color: Option<Option<String>>,
+    pub duration: Option<Option<MediaTime>>,
+}
+
+pub fn find_bookmark_index(bookmarks: &[Bookmark], frame_time: MediaTime) -> Option<usize> {
+    bookmarks.iter().position(|bookmark| bookmark.time == frame_time)
+}
+
+pub fn is_bookmark_at_time(bookmarks: &[Bookmark], frame_time: MediaTime) -> bool {
+    find_bookmark_index(bookmarks, frame_time).is_some()
+}
+
+pub fn toggle_bookmark_in_array(
+    bookmarks: &[Bookmark],
+    frame_time: MediaTime,
+) -> Vec<Bookmark> {
+    if let Some(index) = find_bookmark_index(bookmarks, frame_time) {
+        return bookmarks
+            .iter()
+            .enumerate()
+            .filter(|(bookmark_index, _)| *bookmark_index != index)
+            .map(|(_, bookmark)| bookmark.clone())
+            .collect();
+    }
+
+    let mut next = bookmarks.to_vec();
+    next.push(Bookmark {
+        time: frame_time,
+        note: None,
+        color: None,
+        duration: None,
+    });
+    next.sort_by_key(|bookmark| bookmark.time);
+    next
+}
+
+pub fn remove_bookmark_from_array(
+    bookmarks: &[Bookmark],
+    frame_time: MediaTime,
+) -> Vec<Bookmark> {
+    bookmarks
+        .iter()
+        .filter(|bookmark| bookmark.time != frame_time)
+        .cloned()
+        .collect()
+}
+
+pub fn update_bookmark_in_array(
+    bookmarks: &[Bookmark],
+    frame_time: MediaTime,
+    updates: &BookmarkPatch,
+) -> Vec<Bookmark> {
+    let Some(index) = find_bookmark_index(bookmarks, frame_time) else {
+        return bookmarks.to_vec();
+    };
+
+    let mut next = bookmarks.to_vec();
+    let bookmark = &mut next[index];
+    if let Some(note) = &updates.note {
+        bookmark.note = note.clone();
+    }
+    if let Some(color) = &updates.color {
+        bookmark.color = color.clone();
+    }
+    if let Some(duration) = &updates.duration {
+        bookmark.duration = *duration;
+    }
+    next
+}
+
+pub fn move_bookmark_in_array(
+    bookmarks: &[Bookmark],
+    from_time: MediaTime,
+    to_time: MediaTime,
+) -> Vec<Bookmark> {
+    let Some(index) = find_bookmark_index(bookmarks, from_time) else {
+        return bookmarks.to_vec();
+    };
+
+    let mut next = bookmarks.to_vec();
+    next[index].time = to_time;
+    next.sort_by_key(|bookmark| bookmark.time);
+    next
+}
+
+pub fn get_frame_time(time: MediaTime, fps: FrameRate) -> MediaTime {
+    time.round_to_frame(fps).unwrap_or(time)
+}