Reuse MCP tool catalogs across sessions

[copyberry]

Reuse MCP tool catalogs across sessions

Why

Starting a new session should not have to wait for an unchanged stdio MCP
server to initialize before its tools can be presented to the model.

What changed

• Cache recent tool catalogs for matching stdio MCP server configurations and
  use them while a new live connection starts in the background.
• Bound the process-wide cache to 32 entries with a 30-minute TTL, and key
  entries by the server configuration, environment, working directory, and
  elicitation capabilities that affect the catalog.
• Keep connection-specific instructions and tool annotations out of cached
  catalogs. Resolve tool calls against the live connection so tools that are
  unavailable or hidden in the new session cannot be invoked from stale data.
• Publish only the newest completed catalog fetch and do not cache HTTP servers
  or stdio configurations that depend on remotely sourced environment values.

Testing

• Add coverage for cache expiration, environment changes, catalog sanitization,
  and out-of-order refreshes.
• Add an end-to-end test that starts inference from cached definitions while a
  replacement MCP process initializes, then verifies calls and visibility
  against the live process.