Reload Footage shows new pixels and keeps Photoshop layers; Reload Footage Changed on Disk

Reload Footage (Cmd+Alt+L) updated an item's metadata but left the media
pool's decoded frames and the layer cache in place, so the old image kept
rendering until Edit > Purge. It also replaced the footage with a probe of
the merged document, so a Photoshop layer item lost its layer and its
Retain Layer Sizes bounds.

Reload now re-reads only what the file decides (size, a movie's duration,
streams and frame rate, codec, a data file's text), keeps the layer or
page and the interpretation, finds a Photoshop layer again by name, and
makes the media layer forget the file (FootageSource::forget, which also
drops the EXR aux-channel cache) and clears the layer cache.

Settings > Import > Reload Footage Changed on Disk (on by default): the
desktop app stamps footage files (size + modification time) on a worker
thread every two seconds and when the window comes back to the front, and
reloads what changed. Not an undo step and it doesn't modify the project;
a file still being written is retried on the next check.
footage.reloadChanged runs one check (CLI, MCP, agents).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/render/src/lib.rs

@@ -61,6 +61,10 @@ pub trait FootageSource: Send + Sync {
     /// Drop the decoded frames it keeps (Edit ▸ Purge ▸ All Memory / Image Cache Memory): the
     /// next reads decode again. Sources without a cache ignore it.
     fn purge(&self) {}
+    /// The file at `path` changed on disk (Reload Footage): drop what it keeps of it (decoded
+    /// frames, open decoders, parsed models), so the next reads see the new contents. Sources
+    /// without a cache ignore it.
+    fn forget(&self, _path: &str) {}
     /// Settings ▸ Disk ▸ Conformed Audio Folder: where decoded audio is kept between reads
     /// (`None` = off); sources that don't decode audio ignore it.
     fn set_conform_folder(&self, _folder: Option<std::path::PathBuf>) {}