fix: exclude_concepts should filter patterns and principles in recall results

[CalebisGross]

Problem

When using exclude_concepts on the recall MCP tool, memories are correctly filtered but the patterns and principles sections of the response still include items matching excluded concepts.

Example: recall({query: "retrieval ranking", exclude_concepts: ["training", "felixlm"]}) correctly omits training memories, but the patterns section still returns "Iterative Felix-LM Training Optimization".

Expected

exclude_concepts should filter all result sections: memories, patterns, and principles.

Implementation

In internal/mcp/server.go handleRecall, apply the same exclude filter to pattern and principle results before building the response.

[CalebisGross]

Fixed in #324 — exclude_concepts now filters patterns and abstractions in recall results, not just memories.