Document processing: status, configure and test can start the local gateway through ensure() before any decision is shown #356

From the narrow second-reviewer round on #355 (finding 2, MEDIUM; the behaviour predates #355). localGatewayStatus calls ensure(), which starts the local gateway once the 5 s retryAfter has passed; that happens on status, configure and test before the 409 check. A page that showed unavailable and saved with restartWarned false gets a 409 if the gateway is ready by then (no unwarned restart), but the start itself is a side effect of a read, and no test covers the unavailable-to-ready path. Fix sketch: a read never starts the gateway; a start happens only on an owner's action that says so; a test for the unavailable-to-ready save path.