Add agent name and trigger information below session title in header

Steps to reproduce

• Navigate to AI Panel > Sessions
• Open any session to view the session detail page
• Observe the header area below the main session title
• Note that agent information and who triggered the session is missing from the header

Current behavior

• Session header only shows the basic session title (e.g., "Agent session #1205369")
• No indication of which specific agent is involved in the session
• Missing information about who triggered or initiated the session
• Users must look elsewhere in the interface to find this contextual information

Expected behavior

• Add a subtitle line below the main session title showing agent details Include format similar to: Duo Planner #887
• Show trigger information like: @sarah triggered Duo Planner June 1, 2025
• This information should be prominently displayed for quick reference

Design