feat(versions): link at ingest, hide in listings, version endpoints

XMP (PNG iTXt DerivedFrom, native chunk reader) then file-name convention
links at ingest; unlinked name candidates are retried each tick. Versions
are hidden from /photos (SQL for the recursive listing, hidden-row set for
the walk and tag branches), /memories, reels, /photos/exif, the GPS summary,
unified search and the media gauges while their original is reachable in the
view; include_versions=true lists them. /photos gains the parallel arrays
photo_display_paths / photo_version_counts, memories / search hits /
/photos/exif rows gain display_path / version_count, all skipped when empty.
GET /image/versions and PUT /image/versions/display (library optional).
Tags and favorites on a version path bind to the original; faces, CLIP and
duplicate grouping skip version hashes; insight generation redirects to the
original. Orphan GC and the back-ref refresh cover the new tables.

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

src/handlers/favorites.rs

@@ -44,6 +44,8 @@ pub async fn favorites(
                 photos: favorites,
                 dirs: Vec::new(),
                 photo_libraries: Vec::new(),
+                photo_display_paths: Vec::new(),
+                photo_version_counts: Vec::new(),
                 total_count: None,
                 has_more: None,
                 next_offset: None,