Hide Help launcher in docs captures

The docs capture helper (apps/docs/capture/capture.mjs) hides sticky/fixed elements that overlap a shot's clip, but the Help launcher (the "Ask Jarvis" orb, data-testid="help-launcher") still shows in the bottom-right corner of figures near the viewport bottom — seen on People's Account card (administration/people-and-orgs/img/people/account.png, desktop 1440x900). Switching the hide from an inline style to an attribute + stylesheet did not help, so the launcher likely mounts or slides in after the overlap pass. Suggestions: 1. Hide `[data-testid="help-launcher"]` (and any floating dock/orb) for every shot unconditionally, via an injected stylesheet applied before the shutter. 2. Retake People's account.png once fixed. Out of scope: any console behaviour change to the launcher itself; other docs pages. Done means: a capture of people.shots.json's `account` shot shows no orb; `npm test --prefix apps/docs` green.

Capture helper now hides the Help launcher on every shot via an injected stylesheet in preShutter; retook People account.png (no orb). npm test 27/27, quick gate green; PR #6501 queued to the merge lane. Visual check done: orb gone.