Adds centralized option validation for ZoneTree configuration. - #149

Summary

Adds centralized option validation for ZoneTree configuration.

This hardens startup validation by checking required options, enum values, compression method/level compatibility, and unsafe numeric ranges before ZoneTree opens.

Details

• Adds a dedicated ZoneTreeOptionsValidator
• Adds centralized editable validation rules via ZoneTreeOptionValidationRules
• Adds compact fluent Rule helpers for min/max, KB/MB, and seconds-based ranges
• Adds AllowUnsafeOptionValues for tests and advanced users who intentionally want to bypass numeric range checks
• Keeps required options, enum validation, and compression compatibility always enforced
• Adds focused tests for valid options, missing options, invalid values, compression validation, and unsafe bypass behavior
• Improves XML comments for critical options that affect memory, segment shape, and multipart behavior

Notes

This is defensive validation and documentation cleanup. It does not change normal runtime behavior for valid configurations.