STOP browser test (playwright): drag, STOP, resume on the real page, recorded stream matches #73

Part (c) of #66. The gate, the relay and the arm server are covered by src/stop.test.ts (property test and 100-command replay against a fake Pi). Still missing: a playwright run of the real page at 390x844 and a desktop size, against bench/fake-serve.ts with a fake Pi as ARM_SERVER: drag a joint on the 3D model, press the one [data-stop] (pointerdown), tap Resume twice, drag again. Assert the fake Pi's recorded targets: frames from before STOP, then nothing until a frame stamped after the resume. Attach the recorded stream to the pull. Needs playwright and a browser in the check; say in the README why the dependency is there.

Parked by the crew: the run ended without a pull: declined: the work this test depends on isn't on main or on this branch, so there is nothing for the browser test to check.

Parked by the crew: the run ended without a pull: declined: nothing has changed since the last decline, so there is still nothing for the browser test to check.

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the run ended without a pull: declined: the work this test depends on isn't on main or on this branch, so there is nothing for the browser test to check
2. the run ended without a pull: declined: nothing has changed since the last decline, so there is still nothing for the browser test to check

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Steward: paused - this needs the crew to reach the app's public URL or the real Pi, which the sandbox cannot yet (trevato/forge#3658 own app hosts, #3470 device SSH). Closing so it stops being retried and reported; reopen when those land.