Port from anomalyco/opencode#34529: MCP servers can emit
notifications/message logging notifications (RFC 5424 levels), but the
MCP SDK's default logging_callback silently discards them — server-side
warnings/errors during tool calls were invisible.
- tools/mcp_tool.py: pass a logging_callback to every ClientSession
(stdio, SSE, streamable HTTP old+new API paths via the shared
sampling_kwargs sites), mapping the 8 MCP log levels onto Python
logging levels and tagging entries with [server/logger] origin.
- JSON-serialize non-string payloads, cap at 2000 chars so a chatty
server can't flood agent.log, never raise from the handler.
- Gated on SDK support (_check_logging_callback_support) mirroring the
existing message_handler gate for old SDK versions.
- tests/tools/test_mcp_server_log_notifications.py: 10 tests covering
level mapping, origin tagging, JSON payloads, truncation, and the
never-raise contract.
