Add planning phase and separate queen/worker tool docs

[RichardTang-Aden]

Summary

• Add a planning phase to the queen with read-only tools and a dedicated knowledge prompt for collaborative goal-setting before building
• Add a "Worker File Tools" section to the queen's building knowledge so it references correct hive-tools MCP names for workers instead of its own coder-tools names
• Add replan_agent lifecycle tool and frontend phase state display

Closes #6049

Test Plan

• Verify queen starts in planning phase with read-only tools
• Verify queen transitions to building phase with full tool set
• Verify replan_agent returns queen to planning phase
• Verify worker prompts reference hive-tools names (view_file, write_to_file, etc.) not coder-tools names
• Verify frontend displays current phase state