Add AI agent panel with flow editing tools

[adilhbay]

Summary

• AI Agent Panel: Integrated a resizable agent panel into the flow editor with streaming OpenAI responses, markdown rendering (GFM), and selected node awareness displayed as chips above the input field
• Comprehensive Tool System: Built a full suite of agent tools — create, update, delete, and connect nodes (HTTP, JS, condition, for/forEach, AI), with anti-destructive guardrails, expression auto-transforms, and auto-layout
• TypeSpec AI Tool Schema Generation: Added a new @explorationTool / @mutationTool decorator system with an Effect Schema emitter, enabling declarative tool definitions derived from collection models
• Bug Fixes: Resolved sync race conditions, stale closures, layout cycle detection, edge deletion, excessive re-renders, and message overflow issues in the agent subsystem

CI Status

All checks pass with the exception of root:lint:format. The formatting differences flagged by this check are confined to files outside the scope of this PR — files that were neither introduced nor modified as part of this work. To maintain a clean diff and avoid unrelated changes, these pre-existing formatting discrepancies were intentionally left untouched.

Test plan

• Verify the agent panel opens in the flow editor and streams responses correctly
• Test node CRUD operations (create, update, delete) via agent tool calls
• Confirm node connections (sequential, fan-out/fan-in) via connectChain
• Validate selected nodes appear as chips in the agent input area
• Check light/dark theme support across the agent panel

🤖 Generated with Claude Code

[Tomaszal]

Closed in favor of #37