Closes cumulative review 46-48 F1 (Medium) + F3 (Low). Adds
iso_ts_from_clock(clock) alongside iso_ts_now() in the Layer-1
helper; migrates four duplicate definitions in c2_vpr (net_vlad,
ultra_vpr, _faiss_bridge) and c12_operator_orchestrator
(operator_reloc_service). Output format flipped +00:00 -> Z to
align with iso_ts_now() and the canonical FDR _TS fixture (FDR
schema test passes unmodified).
18 helper AC tests + 186 sibling tests pass; ruff clean.
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh