fix(mcp): restart prestarted provider after config changes

[astyfx]

Summary

• Ensure MCP configuration edits made after provider startup take effect on the first turn.
• Prevent a prestarted process from using a stale native configuration snapshot.

Changes

• Track provider process startup time and pass it into MCP refresh checks.
• Compare configuration modification times against process startup during the initial fingerprint check.
• Restart the provider when configuration changed after startup but before the first turn.
• Add regression coverage for initial refresh detection and the prestarted-process lifecycle.

[heath-s]

Approved