fix: guard Unix-only fcntl import and SIGKILL lookups

[lars-hagen]

Summary

Applies existing defensive patterns to a few remaining Unix-specific call sites:

• Guard tools/memory_tool.py with the same fcntl/msvcrt fallback already used in scheduler.py and auth.py
• Replace direct signal.SIGKILL lookups with getattr(signal, "SIGKILL", signal.SIGTERM) in 4 files. This only prevents AttributeError on Windows; on Windows, os.kill(pid, SIGTERM) already performs forceful termination, so the runtime behavior is equivalent.
• Update 1 related test assertion to use the same guard

No behavior change on Linux/macOS.

Fixes #5246

Testing

Tested on Windows 11 with Python 3.11, 3.12, and 3.13:

• hermes doctor shows memory tool as available (no fcntl error)
• python -c "import tools.memory_tool; print('OK')" succeeds
• pytest tests/tools/test_memory_tool.py tests/tools/test_mcp_tool.py tests/hermes_cli/test_gateway.py tests/hermes_cli/test_profiles.py -v passes (fixes 1 previously failing test, no regressions)

[alt-glitch]

Implementation PR for #5246. Related to closed #6479 (msvcrt fallback) and open #17965 (LOCK_UN guard).

[alt-glitch]

Implementation PR for #5246.

[teknium1]

Closing as already fixed on main.

Triage notes (high confidence):
All four fixes already on main: memory_tool.py:39-44 has fcntl guard, mcp_tool.py:3548 uses getattr(_signal,'SIGKILL',_signal.SIGTERM), and hermes_cli/profiles.py:1024-1048 routes through terminate_pid() which handles Windows correctly.

If you still see this on the latest version, please reopen with reproduction steps.

(Bulk-closed during a CLI triage sweep.)