Add AgentGrid to AI Coding Tools

[yagudaev]

Adding AgentGrid to the AI Coding Tools section.

• Name: AgentGrid
• URL: https://agentgrid.sh
• What it is: desktop app (Electron; macOS/Linux/Windows) with an infinite, zoomable canvas for running multiple AI coding agents in parallel. A master orchestrator spawns role-based workers (builder, QA, reviewer), each in its own git worktree, alongside integrated terminals and Playwright browser panes. Runs Claude Agent SDK and OpenAI Codex SDK behind a shared worker protocol.