Switch MCP HTTP transport from the deprecated streamablehttp_client()
(mcp < 1.24.0) to the new streamable_http_client() API that accepts a
pre-built httpx.AsyncClient.
Changes vs the original PR #3391:
- Separate try/except imports so mcp < 1.24.0 doesn't break (graceful
fallback to deprecated API instead of losing HTTP MCP entirely)
- Wrap httpx.AsyncClient in async-with for proper lifecycle management
(the new SDK API explicitly skips closing caller-provided clients)
- Match SDK's own create_mcp_http_client defaults: follow_redirects=True,
Timeout(connect_timeout, read=300.0)
- Keep deprecated code path as fallback for older SDK versions
Co-authored-by: HenkDz <HenkDz@users.noreply.github.com>