Harden RemoteOpsX and automate Linux dependency setup

[darwvin-dev]

What changed

Reliability and UI

• fix SFTP parsing for padded ls output, filenames with spaces, and symlinks
• force IdentitiesOnly=yes for SCP key authentication
• keep focused-server state synchronized when tabs close
• correct root's default SFTP home directory
• improve keyboard and screen-reader behavior across tabs, servers, and file actions

Installation and packaging

• add a distro-aware dependency bootstrap for Arch, Debian/Ubuntu, Fedora, and openSUSE
• support runtime and full build/native-protocol dependency modes
• make AppImage installation run the dependency bootstrap first, with explicit confirmation
• declare runtime dependencies in Arch, Debian, and RPM package metadata
• add npm run deps:runtime and npm run deps:build
• document managed-host opt-out with REMOTEOPSX_SKIP_DEPENDENCIES=1

The bootstrap uses only the host's official package manager, prints the exact packages first, and supports --dry-run and non-interactive --yes modes.

Validation

• npm test — 41 tests passed
• npm run build — passed
• npm audit --omit=dev — 0 vulnerabilities
• shell syntax validation — passed
• bootstrap runtime/build dry runs on Ubuntu — passed
• Tauri configuration discovery — passed
• git diff --check — passed

Rust compilation still requires the build dependencies now provided by npm run deps:build.