Refactor TanStack Start’s Cookie & Session Management

[Pranav-Grandhi]

Summary:
Currently, TanStack Start relies on H3's session and cookie APIs, which are functional but limited in flexibility, type safety, and security features. Refactoring TanStack Start to adopt patterns from Remix’s createCookie and createCookieSessionStorage would allow better ergonomics, enhanced control over cookie lifetimes, and support for encrypted/signed cookies.

Benefits:

1. Type Safety: Stronger TypeScript integration to avoid runtime errors.
2. More Control: Flexible cookie management, including configurable expiration times and support for signed/encrypted cookies.
3. Enhanced Security: Out-of-the-box encrypted and signed cookies for safer session management.
4. Ergonomics: A cleaner API that simplifies cookie and session management.

Implementation:

• Replace the current cookie/session APIs with Remix’s createCookie/createCookieSessionStorage.
• Migrate session management to support encrypted/signed cookies.
• Provide documentation and examples for developers.

Potential Risks:

• Breaking Changes: May require adjustments for current users; backward compatibility should be considered.
• Performance: Encryption/signing may introduce some overhead.

This change would modernize and strengthen the core API for handling cookies and sessions, improving security and developer experience.