MCP tool outputs can live in the memory layer

The user’s decision of 2026-10-07 (PLAN.md):

• Saved and recalled per tool. MCP tool outputs can be saved to and retrieved from the memory layer. This is selectable per MCP server and tool, as a scoped setting.
• Screened. The outputs pass the content guard’s screening and labelling at memory admission and at recall. Their provenance is the MCP server and the tool.
• Referenced, not copied. Memory references the ledger’s content and never copies it (U-M2).