Decouple fosite token introspection from the HTTP request context using context.WithoutCancel + 10s timeout. When claude.ai opens multiple concurrent MCP connections and one disconnects, the token validation for subsequent connections no longer fails with "context canceled". Fixes Bug #6 from #bugs-synapbus. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>