Search the knowledge base for patterns, rules, concepts, examples, and anti-patterns.
TRIGGERS: "search for [pattern]", "find [concept]", "what patterns", "how do I refactor", "best practices for", "code smells", "what rules apply to", "show me examples of".
PROACTIVE: Use for any programming question that could be answered by extracted book knowledge.
PREREQUISITE: Knowledge base must be built (references/knowledge/ exists with _search_index.json).