[codex] Add Vanessa TestClient port preflight

[steel-code-agent]

What changed

• Adds fail-fast Vanessa TestClient port preflight while preparing runtime VAParams for launch mcp va and test va.
• Checks local TestClient profiles from ДанныеКлиентовТестирования for busy ПортЗапускаТестКлиента or fully occupied ДиапазонПортовTestclient before launching 1C.
• Includes best-effort Linux PID reporting for the process that owns a busy port.
• Adds a CLI regression proving launch mcp va stops before invoking the platform launcher when a configured local TestClient port is busy.

Why

A Vanessa TestClient launch with an already occupied configured port is known to fail later inside the 1C/VA startup path. The runner already reads VAParams, so it can reject this deterministically before starting additional 1C processes.

Validation

• CC=/usr/bin/gcc cargo test --test cli_launch
• CC=/usr/bin/gcc cargo test test_va_builds_vanessa_command_and_overlay --test cli_test

Note: the default /usr/local/bin/cc in this environment rejects -O0 while building ring; tests pass with CC=/usr/bin/gcc.