feat: Add OAuth proxies

[mschfh]

No description provided.

[Copilot]

Pull Request Overview

This PR adds OAuth proxy functionality for multiple cryptocurrency exchange providers (Gemini, Bitflyer, Uphold, and Zebpay). The implementation includes authentication and token exchange endpoints for both sandbox and production environments, with provider-specific credential injection.

Key changes:

• OAuth proxy endpoints with environment-specific routing (sandbox/production)
• Nested configuration structure using Pydantic for OAuth provider credentials
• Docker Compose setup with Redis for development/testing
• Test configuration with environment file override support

Reviewed Changes

Copilot reviewed 13 out of 17 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pyproject.toml	Added respx testing library dependency
docker-compose.yml	Added Docker services for app and Redis
conftest.py	Created pytest configuration to set test environment variables
app/main.py	Registered OAuth router in the FastAPI application
app/config.py	Added nested OAuth configuration with environment file override
app/api/oauth/routes.py	Created main OAuth router aggregating provider-specific routers
app/api/oauth/models.py	Defined Environment enum for sandbox/production
app/api/oauth/config.py	Implemented nested Pydantic models for OAuth provider configurations
app/api/oauth/gemini.py	Implemented Gemini OAuth proxy endpoints
app/api/oauth/bitflyer.py	Implemented Bitflyer OAuth proxy endpoints
app/api/oauth/uphold.py	Implemented Uphold OAuth proxy endpoints
app/api/oauth/zebpay.py	Implemented Zebpay OAuth proxy endpoints
app/api/oauth/test_bitflyer.py	Added tests for Bitflyer OAuth proxy functionality

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}