Improved Workspace assistant

Add readable OpenAI audit logs

Administrators can enable readable copies of workspace assistant exchanges with OpenAI.

Set WORKSPACE_ASSISTANT_AUDIT_OPENAI=true to add multiline request and response entries to the application log. The entries show instructions, conversation items, tools, arguments, results, and assistant output in a readable format. Request headers, credentials, CSRF values, and encrypted reasoning content are omitted. The setting remains off by default because workspace content can appear in these entries.