Rewrite workshop 05: Composition #332

Part of #326.

Questions

• Layers, drawings, sketches, looks, bakes
• One home for the view modes mask/frame/fit/raw
• Frame space vs. photo space
• Rendering for the phone

As-is sources

layers, sketches, step_bakes, apps/studio/src/compose/, docs/features/composition.md, compose.md

Format

No product code. I prepare docs/rewrite/05-composition.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.