JS-043 MED: bin/*.js helper consolidation + clarity cleanup

The JS be status/be get extensions duplicate small helpers across 12 files and carry some dead/awkward code. Consolidate into shared libs and remove the cruft — pure bin/*.js, NO behavior change (the be-bin-* / be-js-get-* parity tests stay byte-for-byte green). Disjoint from JS-042/JS-044 (touches no js/ C, adds no bindings). Found by the bin/*.js review. Method: Issues.

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