Fixed regexrule and timezonerule inconsistencies

[sn]

This pull request makes several improvements and fixes to the nitro_validator package, focusing on validator instance isolation, rule parsing, and increased robustness of built-in rules. The most significant change is that each NitroValidator instance now gets its own independent rule registry by default, preventing rule registrations from leaking across instances. Additionally, the built-in rules are improved for correctness and clarity, and the handling of custom error messages is made safer.

Validator instance isolation and registry handling:

• Each NitroValidator now receives a fresh copy of the built-in rule registry by default, so custom rules registered on one validator do not affect others. The registry is copied using a new copy() method on NitroRuleRegistry. [1] [2] [3]

Rule parsing and error handling:

• Improved error handling and documentation for rule string parsing, clarifying that pipe (|) and comma (,) characters cannot appear in rule arguments, and that rules needing such patterns (like regexes) must be passed as instances. [1] [2]
• The RegexRule now compiles its pattern at initialization, and fails validation if the pattern is invalid or missing.

Built-in rule improvements and bug fixes:

• The IpRule now uses precompiled patterns for IPv4 and IPv6, and checks both correctly. [1] [2]
• All numeric rules (MinRule, MaxRule, BetweenRule, PositiveRule, NegativeRule) now explicitly reject boolean values, which previously could be incorrectly accepted as numbers. [1] [2] [3] [4] [5] [6] [7]

Custom error message handling:

• Custom error messages for rules are now applied in a way that prevents them from leaking between validations, by temporarily overriding the rule's custom_message attribute.

Documentation and minor cleanups:

• Various docstring and comment improvements for clarity and accuracy, including details on rule syntax and usage. [1] [2] [3] [4] [5] [6]

These changes improve the reliability, safety, and clarity of the validation framework.