docs(snapshots): Correct ImageMetadata CLI-managed fields list

[runningcode]

Summary

• The doc comment on ImageMetadata listed image_file_name as a CLI-managed override, but no such field is written by the CLI.
• ImageMetadata::new only sets width and height; the Sentry backend derives image_file_name from the manifest map key, not from a metadata field.
• Updates the comment to match reality.

🤖 Generated with Claude Code

[cameroncooke]

Yep I've confirmed image_file_name is not used. LGTM!

[cameroncooke]

Claude backs this up:

The sentry-cli pairs a sidecar JSON with an image purely by filename-stem match in the same directory — button.png loads button.json via image_path.with_extension("json"), so image_file_name is not needed (and can't be used) to match JSON to images (sentry-cli/src/commands/build/snapshots.rs). The server-side typed sidecar shape is ImageMetadata with display_name, group, content_hash, width, height plus extra = "allow" for arbitrary passthrough keys (manifest.py), but the CLI overwrites content_hash, width, and height before upload, which leaves only display_name and group as genuinely user-settable sidecar fields (confirmed by the JS fixture snapshot-image-metadata.ts); image_file_name is actually the key of the manifest images dict (the image's relative path), and the GET response explicitly rebuilds it from that key while stripping any image_file_name you smuggled through the sidecar's extras (preprod_artifact_snapshot.py, comparison_categorizer.py, and see the CLI's own note in snapshots.rs data types).