Apply connect-timeout to WebSocket dialing

[ryanfowler]

Summary

• Thread --connect-timeout through the WebSocket dial path and cap it by any remaining --timeout budget.
• Apply that budget to custom DNS lookup, TCP connect, proxy CONNECT, SOCKS5 negotiation, and TLS/WebSocket handshake setup.
• Add unit and integration coverage for stalled DNS and proxy cases, and update the WebSocket docs and agent notes.

Testing

• cargo fmt
• cargo clippy --locked --all-targets --all-features -- -D warnings
• cargo test --all-features
• cargo test --all-features --test integration -- --test-threads=1