batter 0.10.1 — live tick mode

Additive (ENGINE_VERSION stays 0.9.0 — zero receipt impact). TickRequest.mode='live' (ADR-0050 L1 Path A): identical decision path to a single branch point at the fill boundary; emits target_positions {instrument_id, side, target_shares, signal_price, source_manifest_id} with rule-151 provenance; guards gate live intents exactly as paper fills; paper callers byte-unchanged. 824 tests, 6-OS matrix.