doc: add adr

[felipemelozx]

Pull Request Description

The Architectural Decision Record (ADR) has been added, documenting the architectural decisions and implementation plan for the financial management project. The decisions cover code organization, frameworks, authentication, database, infrastructure, and alternatives considered.

Related Task

Resolves #4

What was done?

The ADR was added, documenting the architectural decisions and implementation plan for the project. The document covers everything from backend code organization to frontend technologies, CI/CD, security, database, and infrastructure, such as the use of Terraform for AWS resource management and integration with CI/CD via GitHub Actions.

Tests

• I tested the new feature/fix locally.
• I documented the tests, if necessary.

How to Test

This PR does not include code changes, only the documentation. To validate, simply review the content of the ADR to ensure all architectural decisions are correct and aligned with the project.

Dependencies

No additional dependencies are required for this PR, as it is solely focused on documenting architectural decisions.

Useful Links

N/A