#470 Code Quality: Module constant lists should be tuples for immutability

Three module-level constants are defined as lists but never modified. Should be tuples: 1. engine/security/platform.py:105 - PLATFORM_ROLES = [...] 2. engine/security/rbac_roles.py:75 - PREDEFINED_ROLES = [...] 3. engine/config.py:660 - TOOLS_REQUIRING_LOGGING = [...] FIX: Change [...] to (...) to: - Prevent accidental mutations - Signal immutability intent - Enable hashability where needed