refactor: use _should_sanitize_tool_calls in run_conversation()

Replaces hardcoded Mistral check with the new _should_sanitize_tool_calls()
method. Updates comment to mention Fireworks alongside Mistral as strict
APIs requiring tool_call field sanitization.

run_agent.py

@@ -6810,10 +6810,10 @@ class AIAgent:
                 if "finish_reason" in api_msg:
                     api_msg.pop("finish_reason")
                 # Strip Codex Responses API fields (call_id, response_item_id) for
-                # strict providers like Mistral that reject unknown fields with 422.
+                # strict providers like Mistral, Fireworks, etc. that reject unknown fields.
                 # Uses new dicts so the internal messages list retains the fields
                 # for Codex Responses compatibility.
-                if "api.mistral.ai" in self._base_url_lower:
+                if self._should_sanitize_tool_calls():
                     self._sanitize_tool_calls_for_strict_api(api_msg)
                 # Keep 'reasoning_details' - OpenRouter uses this for multi-turn reasoning context
                 # The signature field helps maintain reasoning continuity