Add recall filters: by entity type, by source, by confidence threshold

[josharsh]

Summary

Currently recall() accepts query, limit, bankId, and time filters. In practice, users need more granular filtering:

• By entity type — "recall only facts about people" or "only facts about companies"
• By source — "recall only facts from Slack" or "only facts from meetings"
• By confidence — "recall only facts with confidence > 0.8"

What needs to happen

1. Extend the RecallOptions type in src/types.ts with optional filter fields:

   entityType?: string;      // filter facts linked to entities of this type
   source?: string;          // filter by source field
   minConfidence?: number;   // minimum confidence threshold

2. Update the recall pipeline in src/pipelines/recall.ts to apply these filters
3. Update the MCP server in src/mcp/server.ts to expose these as tool parameters
4. Add tests in tests/

Files to look at

• src/types.ts — RecallOptions interface
• src/pipelines/recall.ts — the recall pipeline
• src/store/store.ts — underlying queries
• src/mcp/server.ts — MCP tool definitions

Acceptance criteria

• recall({ query: '...', entityType: 'person' }) returns only person-linked facts
• recall({ query: '...', source: 'slack' }) filters by source
• recall({ query: '...', minConfidence: 0.8 }) filters low-confidence results
• Filters combine (AND logic)
• MCP recall tool accepts the new parameters
• Tests for each filter and combinations