* test(ui): close each federation spec API connection so the proxy cannot drop an idle keep-alive socket
* test(ui): send Connection: close on every integration browser spec API call
* test(ui): send Connection: close on every integration browser request from the Playwright config
Adds integration contracts for MCP lifecycle, protocol errors and OAuth
configuration, A2A wire versions, the OpenAI consumer path, persisted
toolsets, callback delivery, guardrail effects, configured prices, the
filtered spend ledger, and a CircleCI-owned browser flow for project
detachment, with the ASGI, browser-state, client and MCP helpers they use.
Consolidates the eleven commits previously stacked on
litellm_integration_providers onto its rebased tip
