fix(mobile): enable HMR by removing default custom-protocol feature + update docs
Remove custom-protocol from default Cargo.toml tauri dependency — dev builds
now respect devUrl for HMR, release builds explicitly add --features custom-protocol.
Rewrite DEVELOPMENT.md iOS section with accurate two-pathway documentation.
Fix dev-setup.sh to auto-build libraries if missing. Clean stale devUrl from
tauri.conf.json.