Add AG2 (formerly AutoGen) multi-agent runtime

[VasiliyRad]

Adds AppType.AG2 as a third runtime alongside the existing LangGraph and CrewAI runtimes. Implements ag2/builder.py (parallel to crew/builder.py) with three orchestration modes: two-agent, group chat, and reasoning. Includes platform tool adapter, Socket.IO streaming integration, LLM config bridge, and a webapp form component for mode selection. Uses AG2 v0.11+ with Docker sandbox for safe code execution.

Why: AgentCloud currently supports LangGraph (stateful graph workflows) and CrewAI (role-based crews), but both use a central orchestrator that decides turn order at design time. AG2 fills a gap with conversational multi-agent patterns — GroupChat with LLM-driven dynamic speaker selection and ReasoningAgent with built-in tree-of-thought. ReasoningAgent has no equivalent in LangGraph or CrewAI and is the clearest differentiator for complex planning tasks. The implementation follows the existing crew/ module pattern exactly (builder + runner + streaming), so the integration surface is well-defined and the review scope is contained.

Files added: agent-backend/ag2/ (4 files) + webapp/src/components/AgentCloudAG2Form.tsx
Files modified: agent-backend/models/apptype.py, agent-backend/router.py

[VasiliyRad]

@iandjx, could you please review this change? It adds AG2 as a new multi-agent runtime alongside LangGraph and CrewAI.

[iandjx]

@VasiliyRad is this deployed to the cloud? How do i test it out? thanks

[VasiliyRad]

@VasiliyRad is this deployed to the cloud? How do i test it out? thanks

Not on cloud yet. To test: run locally, go to Apps → New App → Process App — AG2 is now one of the framework options. Create an app with agents/tasks, save, and hit Play.