feat(erc7730): D-I iteration and signer-constant intent check

[BitHighlander]

Scope

D-I iteration compiler mirror, stacked on D-G #117. Enables one array reached through tuples, requires every iterating formatter path to bind to the active value array, and retains fixed-array coverage.

The split audit found the old D tuple check read mixed_arrays instead of value_literal. It now checks the fourth member. The inherited signer-constant regression fails with the old code and passes with the fix. Firmware already rejected the malformed intent.

Validation

18 compiler/validator cases pass without skips, including 1,450 registry formats and 1,273 signable. The group/optional controls and signer-constant regression remain in this child. Preserves historical #115; new review unit starts with zero attempts.

[BitHighlander]

Consolidated 7b Python companion #119 now compares the unchanged final pin 5c2dd4d against the published phase-0 base. Closing this superseded narrow PR preserves its commits and branch as historical audit evidence. Firmware consolidation is #871; no product or release merge occurred.