OAuth authorization was only handled in MCPTool.Execute, so unauthenticated
services failed silently during RegisterMCPTools before any tool reached the
agent. Wire EventBus/session metadata into registration and reuse the same
getOrCreateMCPClientWithOAuthRetry path used at execution time.
Extract MCP OAuth session/wait/connect logic into mcp_oauth.go and remove the
duplicate waitForOAuthAndRetry + RegisterMCPContext layering in mcp_tool.go.
wizardchen
505195865a