Leader teleop: with the leader connected in Chrome, moving it moves the real arm - live, during your turn #56

Owner, 2026-10-20 21:20Z: "leader connection works well in chrome but it doesnt appear to do teleop. i want that too." The Web Serial connection (#18) reads the leader; its pose is not turned into follower commands.

Done:

1. A "Teleop" switch next to "Connect leader arm": on during your turn, the leader pose (read at ≥ 60 Hz) is mapped through the driver's calibration (#19) and sent as joint targets over the single WebSocket from #54 - coalesced to 30 Hz, latest-wins - with the gripper mapped too.
2. The owner (forge-signed admin) can teleop any time without queueing ("Take control" ends the current turn, as in #16); everyone else teleops only on their turn.
3. Safety (#11) still clamps; on taking control the follower eases to the leader's pose (max speed) instead of snapping; teleop off, tab hidden, serial unplugged, or socket lost → zero motion and hold.
4. The leader's live mirror and the follower's real pose are both drawn so lag is visible; the #54 metrics include leader→follower lag p50/p95 (target p95 < 200 ms on home wifi).
5. Tests: a fake serial leader moves the simulated follower through the same path; outside your turn nothing is sent; unplugging stops motion within one frame.