Phone portrait: the video is pinned on top with its 16:9 box reserved, and one status strip sits under it (from main at 1142ee6 or later, forge.json untouched) #176

Replaces #112. Pull #115 failed only because of the old forge.json check block with no check.run, which main fixed in 1142ee6; its deploy and tests passed. Branch quill/112-phone-portrait-the-video-is-pinned-on-to has the code. Take it without its forge.json change.

Done, at 390x844 and 412x915 portrait (@media (max-width: 600px) and (orientation: portrait)):

• [ ] The camera pane is full-bleed and position: sticky; top: 0, with aspect-ratio: 16/9 reserved before the first frame, so nothing moves when it arrives.
• [ ] Directly under it there is exactly one status strip (driver + time left, your queue place, live/reconnecting), reusing values the page already shows; duplicate status lines are hidden on phones.
• [ ] viewport-fit=cover and env(safe-area-inset-*) are respected. The rules live in Software/so101/src/ui/mobile.css, linked from viewer.html. Desktop is unchanged.
• [ ] A test checks that the stylesheet is served and linked (200, text/css); existing tests pass.
• [ ] Branched from current main; the diff does not touch forge.json. bun --cwd Software/so101 test and bun x tsc --noEmit pass.