Closes gap-analysis v2 §7.6 / §10.7.
- Adds DEFAULT_PHASE_TIMEOUTS: Record<TransactionState, number | null>
to orchestrator/src/types/transactionState.ts, covering all 12 states
of the §8 state machine with rationale-per-state comments.
- getPhaseTimeoutMs(state) honours per-state env overrides
(PHASE_TIMEOUT_<STATE>=<ms>; '0' disables; invalid → default).
- CLOSED is the only state with a null (no-timeout) value.
- 9 unit tests; full suite passes.
