Refactor event and session column names to camelCase

- Updated test cases to reflect new column names (eve_MAC -> eveMac, eve_DateTime -> eveDateTime, etc.) across various test files.
- Modified SQL table definitions in the database cleanup and migration tests to use camelCase naming conventions.
- Implemented migration tests to ensure legacy column names are correctly renamed to camelCase equivalents.
- Ensured that existing data is preserved during the migration process and that views referencing old column names are dropped before renaming.
- Verified that the migration function is idempotent, allowing for safe re-execution without data loss.

.github/skills/code-standards/SKILL.md

@@ -12,6 +12,7 @@ description: NetAlertX coding standards and conventions. Use this when writing c
 - code has to be maintainable, no duplicate code
 - follow DRY principle - maintainability of code is more important than speed of implementation
 - code files should be less than 500 LOC for better maintainability
+- DB columns must not contain underscores, use camelCase instead (e.g., deviceInstanceId, not device_instance_id)
 
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