Implement Financial Contributions and Payments

[reyraa]

Implement the API to handle financial contributions from fans to support artist projects.

Parent

• Add support for projects #7

Acceptance Criteria:

• API endpoint to process financial contributions.
• We'll iIntegration with a payment gateway (e.g., Stripe, PayPal) later on with IIntegration with a payment gateway #32.
• Validation to ensure contributions match defined tiers.
• Store contribution records linked to the user and the project.
• Documentation of the financial contribution process and related API endpoints.