In Compare a filmstrip click made the clicked photo active without
showing it, so the Edit panel and the rating keys acted on a photo on
neither side (a headless test rated the hidden photo 2 -> 3 stars). The
click now puts the photo into the active side (the candidate after
entering Compare, the select after clicking the select's photo); a photo
already on the other side swaps the two. The active photo is always one
of the two shown. Other views keep the usual selection clicks.
New UI command compare.set {id, side?: "select" | "candidate"} for the
same through the control channel and MCP.
New headless tests in tests_compare.rs: the active photo stays on screen
and no hidden photo is rated (Fit and 100 %), and replace / swap /
explicit side / unknown side.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
