fix(physics): use predicted magnetic gate bounds

Correct the readable 1000:9b69 reconstruction to read DGROUP 07db/07df and name the helper for its predicted-position role. Rust magnetic rectangles now enter only from an old position inside the record and deactivate when the recomputed prediction exits any edge, replacing the prior swept approximation.

Test Plan:
- bash original/tools/test_reconstructed_c.sh
- python3 original/tools/audit_reconstruction.py --require-complete
- cargo test --all-targets
- cargo clippy --all-targets --all-features -- -D warnings
- rumdl check original/C_RECONSTRUCTION_FINAL_AUDIT.md tdkpin-rs/CHANGELOG.md tdkpin-rs/RECONSTRUCTION.md tdkpin-rs/README.md
- git diff --check

original/C_RECONSTRUCTION_FINAL_AUDIT.md

@@ -71,6 +71,11 @@ the original Borland compiler.
     multiball, and scoring. Static/host evidence is not mislabeled as Wine.
 12. **Phase boundary:** no Rust source or Cargo manifest/lockfile was modified.
 
+Post-audit evidence correction (2026-08-23): raw `1000:9b69` reads predicted
+DGROUP coordinates `1028:07db/07df`, not current `07d3/07d7`. The readable
+helper and its harness now reflect that distinction; the complete C test and
+ledger gates below still pass.
+
 ## Reproducible gates
 
 ```sh