Phase 5e bridge split closed. x2d_bridge.py is now a 255-LoC pure
back-compat re-export shim; every handler lives under its canonical
beambam.* home.
LoC drained from the monolith in v1.4.0: 3,470 → 255 (−93 %).
See CHANGELOG.md for the full per-batch ledger.
No breaking changes — every from x2d_bridge import X continues to
work via the re-export shim.