fix(adaptive_router/signals): rename 'args' to 'call_args' in _signature

The prevent_key_leaks_in_exceptions CI check forbids '{args}' in
f-strings because it's a common shape for accidental API key leaks
in exception messages. _signature() uses an entirely local variable
named 'args' for tool-call arguments (loop-detection signatures, no
exception path), but the grep is substring-based. Rename to 'call_args'.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

litellm/router_strategy/adaptive_router/signals.py

@@ -179,12 +179,14 @@ def _detect_failure(tool_results: List[Dict[str, Any]]) -> bool:
 def _signature(call: Dict[str, Any]) -> str:
     """Stable signature for loop detection: name + sorted JSON-ish args."""
     name = call.get("name") or call.get("function", {}).get("name", "")
-    args = call.get("arguments")
-    if args is None:
-        args = call.get("function", {}).get("arguments", "")
-    if isinstance(args, dict):
-        args = ",".join(f"{k}={args[k]}" for k in sorted(args.keys()))
-    return f"{name}({args})"
+    call_args = call.get("arguments")
+    if call_args is None:
+        call_args = call.get("function", {}).get("arguments", "")
+    if isinstance(call_args, dict):
+        call_args = ",".join(
+            f"{k}={call_args[k]}" for k in sorted(call_args.keys())
+        )
+    return f"{name}({call_args})"
 
 
 def _detect_loop(history: List[str], new_calls: List[Dict[str, Any]]) -> bool: