Tighten approve-endpoint to active shares with TTL sessions, reject non-file
FDs, lower default ticket/approval/size caps, show endpoint IDs and Public-mode
warnings, harden Android receive path checks, and run cargo-audit in CI.
Add a path-filtered Shared KMP workflow so receive/send ViewModel and
Compose foundation regressions fail CI. Runs on macOS arm64 because host
Rust embedding for Linux JVM is disabled in the Gradle cargo config.