test(e2e): replace wrapper-integration with in-process interactive test

The old suite spawned bin/ably-interactive (now deleted) to assert wrapper
restart/EIO behaviour. Rewrite as interactive-integration.test.ts covering the
no-wrapper reality: starts/exits cleanly, a real SIGINT interrupts a running
command and the SAME process re-prompts and stays usable, and `exit` emits 42
under ABLY_WRAPPER_MODE (the host restart-loop contract). Real-terminal SIGINT
and terminal-corruption/EIO coverage lives in
test/tty/commands/interactive-sigint.test.ts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: umair-ably