V48 Gate 3 (specification-only): Full-stack single-canon SPEC family for rebuild

Open the complete V48 draft family (SPEC + DELTA + NOTES + PARITY + PROVEN)
as Complete Implementation Derivability authority: the entire Bitcode stack
through Gate 3 is restated for rebuild from BITCODE_SPEC_V48.md alone without
silent inheritance from superseded version files. Include Gate 3 SDIVF,
deposit full-stack, demand honesty, and product defaults. Draft status keeps
Current canonical/latest target at active V47 until promotion.

Author: geraldarthurdavis