feat: Add lightweight Node.js document shim and enhance type checking guards

[Patrick-ring-motive]

This PR makes two primary improvements to the CookieStore polyfill:
1. Node.js Compatibility:
• Introduces a lightweight shim for the document object to support environments (like Node.js) where a native document is missing.
• The shim creates a minimal document with a mutable cookie property, allowing the polyfill to operate outside of browser contexts without breaking existing behavior.
2. Enhanced Type Checking:
• Improves type checking guards across the codebase by using helper functions (e.g., isString, isNumber, isNullish, etc.).
• These changes ensure more robust input validation and better error handling without affecting the current API.

Motivation and Benefits:
• Cross-Environment Support:
Developers can now use the CookieStore polyfill seamlessly in both browser and Node.js environments.
• Code Reliability:
The enhanced type guards reduce the risk of runtime errors, making the polyfill more resilient and easier to maintain.

Testing and Backwards Compatibility:
• All changes have been tested to ensure that the polyfill works as expected in environments with a native document as well as in Node.js.
• Existing functionality remains unchanged, preserving backward compatibility.

Please let me know if there are any questions or further adjustments needed.