## What changed
- Correlate MCP server attribution in imported session records with connector
metadata, and persist normalized connector names in the session import ledger.
- Extend `externalAgentConfig/import/readHistories` with connector candidates,
including each connector's display name, imported-session count, and detection
source.
## Testing
- Cover connector detection through the session import and history-read flow.
- Verify candidate aggregation uses the latest import for each source session.
GitOrigin-RevId: 7f1f7f596925b2e6efcd17afd4490148e1ac9ff1
58e4ed17a0