Agent & platform enhancements: multi-bundle, auto-linking, duplicate detection, scheduled curation

[fuseraft]

Consolidated tracking issue for the remaining forward-looking items in docs/features/agent.md ("Future Enhancements") and docs/development/architecture.md ("Planned Enhancements").

• Multi-bundle support — query and search across multiple catalogs; today the agent and CLI operate on one bundle at a time
• Auto-linking — detect implicit relationships across concepts
• Duplicate detection — flag similar or redundant concepts
• Batch operations — update multiple concepts in one agent operation
• Scheduled curation — periodic staleness checks and maintenance (a compendium curate --schedule-style daemon or cron-friendly command)
• Event system — pub/sub for concept changes (architecture.md)
• Plugin architecture — custom agent tools and ingest extractors (architecture.md; distinct from the connector plugin architecture in Connector plugin architecture: IConnector interface + registry #1, which covers sources not tools/extractors)
• Distributed mode — sync bundles across instances (architecture.md)

Auto-linking and duplicate detection likely depend on semantic search (separate issue). Split any of these into their own issue once someone picks it up.