- Extracted Compression Preview from PlaygroundMode lines 506-584 into standalone accordion
- Wrapped in Collapsible with lazy-render (D7): content only mounts after first open
- Accepts inputContent via prop (lifted from TranslateTab in F9) or shows empty-state hint
- POST /api/compression/preview unchanged; error path sanitized (no stack-trace leak)
- 33 Vitest tests covering smoke, lazy-render guard, mode select, fetch dispatch, result grid, error path
