Refactor cache_query_generic() - Separate strategies

[flyingrobots]

Part of SRP Refactoring (Priority 3: Data Processing)

Current Problem

cache_query_generic() in src/cache/query.c mixes initialization, cache attempt, and fallback logic.

Refactoring Plan

Split into:

• query_from_cache() - Cache query only
• query_from_journal() - Journal scan only
• select_query_strategy() - Decision logic

Acceptance Criteria

• Query strategies clearly separated
• Strategy selection isolated
• Each path independently testable
• Fallback logic explicit
• Performance monitoring possible
• Clean interfaces

Technical Notes

• Consider strategy pattern
• Add query performance metrics
• Make strategies pluggable

Related to SRP_REFACTORING_PLAN.md Priority 3.2