fix: honor send_to in Team.run_project

[hiphi730]

Summary

Pass the send_to argument from Team.run_project() to the initial Message.

Previously, the method accepted a recipient but did not forward it, so workflows that need to route the initial requirement to a specific role could remain idle. For example, examples/debate_simple.py passes send_to="Alex", but neither debater reacts when the initial message is broadcast without the intended recipient.

Root cause

Team.run_project() constructed the initial message with only content=idea, silently dropping its send_to parameter.

Tests

• Added coverage for routing the initial project message to a specified role.
• Added coverage for preserving the existing broadcast behavior when no recipient is supplied.
• python -m pytest -q tests/metagpt/test_team.py (3 passed).