fix(xmpp_monitor): exclude key7(kimi) from auto-heal switch candidates

zhiwei must stay on ocg-key6 (deepseek-v4-flash) per user decision.
key7 is kimi — different model provider, incompatible model name.
If best_key returns key7, auto_heal logs skip_switch instead of switching.

scripts/test_key7_guard.py

@@ -0,0 +1,12 @@
+import sys, json
+sys.path.insert(0, '/home/hmo/MoFin')
+import importlib, xmpp_logger
+importlib.reload(xmpp_logger)
+x = xmpp_logger
+print("current provider:", x.current_provider())
+print("KEY_TO_PROVIDER keys:", list(x.KEY_TO_PROVIDER.keys()))
+bk = x.best_key()
+print("best_key:", bk["key_id"] if bk else None, "| total_keys:", bk.get("total_keys") if bk else "-")
+# Simulate: if best key were key7 (kimi), auto_heal must skip switch
+result = x.auto_heal()
+print("auto_heal actions:", json.dumps(result["actions"], ensure_ascii=False))