Show host computer-use permission status on remote clients - #449

Remote clients previously only said to manage Computer Use permissions on the host, leaving users unable to tell whether a host visit was necessary. Settings → Computer Use now queries the attached host and displays separate Accessibility and Screen Recording grants, with Recheck and automatic refresh on reconnect. Grant and restart actions remain on the host. Loading, disconnected, and failed requests never appear as granted or missing permissions; a late response cannot restore a disconnected snapshot.

The existing permission facts move to tcode-core and are re-exported by the native permission facade, keeping one shared representation without bringing native APIs into mobile or Web clients. The facade owns platform applicability, the runtime serves a non-prompting query, and the UI owns request cancellation and localized presentation. Windows reports that separate grants are unnecessary; unsupported hosts are explicit. English/Chinese strings and the design and Computer Use docs are updated.

The regression test drives the production client through literal host messages. It covers mixed grant results, explicit refresh, disconnect cancellation, late replies, reconnect refresh, and a failed recheck replacing an earlier success.

Validation:

• cargo fmt --all --check
• cargo clippy --workspace --all-targets --locked -- -D warnings
• cargo build --workspace --locked
• cargo test --workspace --locked
• cargo-machete . (0.9.2; the installed Cargo wrapper incorrectly passes machete as a directory)
• iOS simulator, Android arm64, and Web target checks with RUSTFLAGS='-D warnings', using the CI commands and NDK 27.1.12297006
• Native macOS client paired to an isolated host: inspected light/dark and wide/compact layouts, exercised Recheck, stopped the host to verify grants disappear, and restarted it to verify automatic recovery.

Local checks above were run before rebasing onto the latest main. CI validates the final PR commit on all configured platforms. Native Windows/Linux permission behavior and changing actual macOS system grants were not exercised locally.