fix: harden simulator workflows and add SOCKS5 proxy support

[Karl-Dai]

Summary

• harden Modbus protocol validation, undefined-address handling, reconnect/scanner behavior, and update checks across the simulator apps
• complete project persistence and runtime restoration for master scan groups, register definitions and values, mutations, and point data sources
• add CI and release workflow checks for formatting, tests, linting, frontend builds, dependency audits, and artifact validation
• add SOCKS5 CONNECT support to ModbusMaster TCP, TCP+TLS, and RTU-over-TCP transports, including IPv4, IPv6, proxy-side domain resolution, optional username/password authentication, and project save/restore

Compatibility and security

• existing v1 project files load with SOCKS5 disabled by default
• disabled proxy settings are omitted from saved project files
• proxy passwords are redacted from Rust Debug output
• the UI warns that RFC 1929 credentials are sent unencrypted to the proxy and stored in project files

Validation

• cargo test --workspace --all-targets — 290 passed
• cargo clippy --workspace --all-targets -- -D warnings
• cargo fmt --all -- --check
• master and slave frontend production builds
• shared frontend tests — 16 passed
• npm audits for all three frontend workspaces — 0 vulnerabilities