refactor(obfuscate): improve type consistency and simplify branch logic

[tetienne]

Summary

• Use sets for key membership checks (O(1) lookup vs O(n) for lists)
• Simplify list iteration in obfuscate_sensitive_data by checking for dict directly instead of excluding other types
• Remove obsolete pylint disable comment
• Use tuple for value membership check since values can be unhashable types

Test plan

• Existing tests pass
• Pre-commit checks pass