fusion/.changeset/fix-planning-mode-streaming.md

@kb/dashboard

@kb/dashboard
minor

Add real-time streaming for planning mode with AI thinking display

• Implement SSE infrastructure for planning sessions (PlanningStreamEvent, PlanningStreamManager)
• Add /api/planning/start-streaming endpoint for AI agent-powered planning
• Add /api/planning/:sessionId/stream SSE endpoint for real-time updates
• Frontend displays AI thinking output in collapsible panel during planning
• Update API client with connectPlanningStream for EventSource management
• Fix infinite spinner issue by ensuring proper state transitions from streaming events