WatchSession.runAll(): Promise<RunResult>
Runs the whole suite, dropping any line-target selectors this session was scoped to.
Not the same as run(): a session started from test/cart-test.ts#34 stays pinned to that
line until something clears the pin, and only this clears it. -t/-m survive — those are a
standing instruction about which tests to run rather than a starting point.
Promise<RunResult>