stripe subscription E2E payment integration

[emmdim]

This commit represents a significant integration of Stripe's subscription payment system, allowing organizations to manage their subscriptions through Stripe's checkout process while maintaining synchronization with the application's database.

Key changes

API Routes & Handlers:

• Added new endpoints for Stripe integration:
  • POST /subscriptions/checkout - Creates new subscription checkout sessions
  • GET /subscriptions/checkout/{sessionID} - Retrieves checkout session information
• Enhanced webhook handling to process subscription events of
  POST /subscriptions/webhook
  • customer.subscription.created
  • customer.subscription.updated
  • customer.subscription.deleted

Database Schema Updates

• Modified OrganizationSubscription structure:
  • Removed EndDate field
• Updated Plan structure:
  * Added StripePriceID field

Error Handling:

• Added new error definition: ErrStripeError

[lucasmenendez]

The code looks good and is well structured. One suggestion, to improve clarity would be to add some comments in the code, not just in the functions and structs declarations, but also around the more complex parts of the logic or third party code.

[lucasmenendez]

some nits