Implement caching layer for database queries

[stranske]

Why

Test Suite C, Test C3 - Duplicate Detection functional test.

Test Suite C, Test C3 - Duplicate Detection functional test.

Scope

Add Redis or in-memory caching to reduce database load for frequently accessed data.

Add Redis or in-memory caching to reduce database load for frequently accessed data.

Non-Goals

Not provided.

Tasks

• Set up Redis connection
• Add cache decorator for query functions
• Implement cache invalidation on writes
• Add cache hit/miss metrics
• Set up Redis connection
• Add cache decorator for query functions
• Implement cache invalidation on writes
• Add cache hit/miss metrics

Acceptance Criteria

• Repeated reads served from cache
• Cache invalidated on data changes
• Metrics show cache hit rate
• Repeated reads served from cache
• Cache invalidated on data changes
• Metrics show cache hit rate
• ---
• Test expectation: Should NOT be flagged as duplicate - completely unrelated topic

</details>

## Implementation Notes

_Not provided._

Original Issue