(U+77F3): Add `<-denotational@usage' for BUCS+77F3.

(U+77F3): Add `<-denotational@usage' for BUCS+77F3.
(UU+77F3): Unify DJT-07954.
(A-IWDSU+4096): New abstract node.
(U+4096): Add `<-denotational' for A-IWDSU+4096; add
`<-denotational@usage' for BUCS+77F3; add `sound@ja/on'.
(UU+4096): Unify HD-JT-B670 and DJT-07955.
(U-0002F94C): Unify HD-KS268410.
(U-00025416): Use `->denotational' and `->subsumptive'; add
`<-denotational@usage' for BUCS+77F3.
(U-00025418): Use ideographic-structure@apparent instead of
ideographic-structure.
(BUCS+77F3): New abstract node; unify A2-DJT-07954.