Rewrite workshop 03: Capture on the phone #330

Part of #326.

Questions

• "The app takes photos" as the base feature (today the shutter is disabled without a rig)
• Camera layouts (generalised viewfinder layouts) and capture profiles that decide which modules are on: frame overlay, optics facet without overlay, position, location/spot assignment, prompts
• Devices as a generic registry with automatic readout
• Upload queue guarantees stay

As-is sources

apps/mobile/src/screens/Viewfinder.tsx, TagEditor.tsx, uploads.ts, device.ts, packages/vocab/src/viewfinder.ts, docs/features/capture.md, viewfinder-layouts.md

Format

No product code. I prepare docs/rewrite/03-capture.md with the as-is state (with file paths), the problems and leaks, a proposal and the open questions; mockups go to docs/rewrite/mockups/. The owner decides, the decisions are recorded in the page's "Decided" section and here, and the PR is merged into rewrite/plan.