feat(agent-team): add team worker report loop

[YingchaoX]

AgentScope Version

2.0.1

Description

Closes #1797.

This PR adds a bounded report loop for Agent Team workers so a team member does not silently finish a task without notifying the leader.

Background:
When a worker completes its assigned task, it is expected to call TeamSay to report the result back to the team leader. In practice, the model can sometimes produce a private final answer and exit without calling TeamSay, leaving the leader waiting and the team task stuck.

Changes made:

• Added TeamReportMiddleware under agentscope.app.middleware.
• Attached the middleware only to team worker agents created with source == "team".
• Added structured team_say metadata to successful TeamSay results so middleware can tell whether the leader was actually notified.
• Treat direct worker-to-leader messages and worker broadcasts as satisfying the report contract.
• Keep reminders bounded to avoid infinite loops.
• Added unit coverage for silent worker finishes, successful reports, peer-only messages, state reset between replies, TeamSay metadata, and ChatService middleware assembly.

How to test:

• Ran local checks:
  • uv run pre-commit run --all-files
  • uv run pytest tests/middleware_test.py tests/service_team_tools_test.py tests/service_chat_middleware_test.py
• Ran local code e2e testing for the Agent Team report flow.
• Ran browser/page e2e testing through the local web UI.
• Verified with screenshots from the page e2e test.

Checklist

• An issue has been created for this PR
• I have read the CONTRIBUTING.md
• Docstrings are in Google style
• Related documentation has been updated (e.g. links, examples, etc.) in documentation repository
• Code is ready for review