Gems 2.0 third-party sprite credits

All 23 gem icons: original frames from Karsiori, FREE Pixel Art Gems Pack - Animated.
CC0 1.0. https://karsiori.itch.io/free-pixel-art-gem-pack
Source pixels were centered on transparent 32x32 canvases without redraw or recolor.

Twelve legendary sprites: RunicPixels, Swordtember 2023 Collection.
CC BY 4.0. https://runicpixels.itch.io/swordtember-2023-collection
https://creativecommons.org/licenses/by/4.0/
These twelve PNGs are unchanged original source files.

Nine further legendary item textures: 7Soul1, OpenClipart contributors, and
AntumDeluge's curated CC0 Ranged, Tool, Jewelry, and Stave Icons packs.
https://opengameart.org/content/cc0-ranged-icons
https://opengameart.org/content/cc0-tool-icons
https://opengameart.org/content/cc0-jewelry-icons
https://opengameart.org/content/cc0-stave-icons
Six PNGs retain source bytes. The other three combine the original bow and
arrow by rotation and translation for the draw states.

Exact source-to-item mappings and archive checksums are in
 tools/adventure/generate_gems_release_assets.py and
 tools/adventure/import_legendary_source_icons.py.
Additional CC0 art and audio credits: see project credits.md.
