Add Edge Case Tests

[jtdub]

Problem

The current test suite covers happy paths and basic error cases, but lacks tests for edge cases that could cause issues in production.

Missing Test Cases

1. Empty configuration files - Should handle gracefully
2. Very large configuration files (10K+ lines) - Should complete in reasonable time
3. Unicode characters in configs - Should handle without encoding errors
4. Identical configurations - Remediation should be empty
5. Whitespace-only differences - Should normalize appropriately
6. Binary/non-text files - Should produce clear error message
7. Special characters in filenames - Should handle spaces and symbols

Acceptance Criteria

• Empty config test added
• Large config test added (with timeout)
• Unicode test added
• Identical config test added
• All tests pass