Adds comprehensive test coverage for the amc_server package:
- test_context.py: Tests _resolve_zellij_bin preference order (which
first, then fallback to bare name)
- test_control.py: Tests SessionControlMixin including two-step Enter
injection with configurable delay, freeform response handling,
plugin inject with explicit session/pane targeting, and unsafe
fallback behavior
- test_state.py: Tests StateMixin zellij session parsing with the
resolved binary path
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
