Refine Search Filtering Engine for Complex Multi-Criteria Queries

## Description
Combining multiple filters can occasionally produce unexpected result sets.

## Proposed Solution
- Normalize filter evaluation.
- Improve query composition.
- Add edge-case handling.
- Strengthen result validation.

## Acceptance Criteria
- Accurate filtered results.
- Predictable query behavior.
- Comprehensive test coverage.

## Expected Labels
`level3`, `NSoC'26`