Add SynapBus to Platforms & Integrated Solutions

[Dumbris]

Summary

• Adds SynapBus to the Platforms & Integrated Solutions section under Community Implementations
• SynapBus is an MCP-native agent-to-agent messaging hub with channels, DMs, semantic search (HNSW), task auction, capability discovery, and a Slack-like web UI
• Single Go binary, relevant to A2A as it enables agent-to-agent communication via MCP tools
• Follows existing entry format with star badge and author link