chore(emoji): ship only resolver-reachable glyphs in graph-compose-emoji (#220)

The module bundled the full Noto Emoji set (3731 SVGs, ~40MB) but
EmojiLibrary resolves glyphs solely through emoji-index.properties, so the
2136 glyphs no shortcode maps to (mostly skin-tone variants 1f3fb-1f3ff)
were unreachable dead weight in a to-be-published Central artifact. Drop
them: 1595 reachable glyphs remain and the packaged jar falls to 3.7MB.
build-emoji-set.py now copies only set(index.values()) so a fresh
regen reproduces the trimmed set directly.

Index unchanged; EmojiRenderTest + EmojiLibraryTest green.

Author: DemchaAV