[Fix] Resolve composite references in inverted index for fast path

[Fix] Resolve composite references in inverted index for fast path

When the inverted index fast path collects potentially active composites,
it scans symbols already in the scan result. Composite symbols are not
yet in the scan result at that point, so composites referencing other
composites as atoms were never activated and silently failed to fire.

Fix by resolving composite references at index build time: recursively
collect leaf (non-composite) atoms and propagate dependent composites
to those atoms' index entries. Also refactor atom name parsing into a
shared helper to reduce duplication.