fix: use HERMES_HOME constant in doctor.py directory check

Line 184 hardcoded Path.home() / ".hermes" instead of using the
existing HERMES_HOME variable which already respects the env var.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hermes_cli/doctor.py

@@ -181,7 +181,7 @@ def run_doctor(args):
     print()
     print(color("◆ Directory Structure", Colors.CYAN, Colors.BOLD))
     
-    hermes_home = Path.home() / ".hermes"
+    hermes_home = HERMES_HOME
     if hermes_home.exists():
         check_ok("~/.hermes directory exists")
     else: