Rendering · RenderSurface: host frames at the box's device pixels, redrawn on a new size or revision, freed from the atlas

TASKS.md

@@ -179,7 +179,7 @@ Per-component lines live in `tasks/`. Tags there:
 - [x] T48m Docs · E2E: the Docs routes, rail, list, previous and next, and code blocks under Playwright
 - [ ] T49 Acceptance: live URL and MVP checklist
 - [x] T50a Rendering · Plan: chapter 44 in the PRD, `tasks/ch44.md`, these lines
-- [ ] T50b Rendering · Surface: `rendering::RenderSurface`, tested — `tasks/ch44.md`
+- [x] T50b Rendering · Surface: `rendering::RenderSurface`, tested — `tasks/ch44.md`
 - [ ] T50c Rendering · Gallery: a Rendering page, its story, `stories.json`; the gallery runs on Linux
 - [ ] T50d Rendering · Web: the story runs live on the site from the wasm gallery, checked in a browser
 - [ ] T50e Rendering · Platforms: CI builds and tests the crate on Linux, macOS and Windows, arm64 and x86_64