- Rename "host styling" section to "host context" and add safe area
insets handling
- Replace abstract `renderLoadingUI`/`renderFinalUI` example with
concrete code preview pattern for `ontoolinputpartial`
- Rename callback parameter `params` → `ctx` for clarity across all
`onhostcontextchanged` handlers
- Add CSS snippet for fullscreen border-radius handling
- Expand display mode example to show `availableDisplayModes` check
- Fix minor typos and wording consistency
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>