refactor: align backend layout and supabase infra

Consolidate backend modules/tests under the backend package while syncing Supabase compose/env config and related plans.

backend/tests/unit/v1/auth/test_auth_service.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import pytest
+
+from v1.auth.models import (
+    AuthTokenResponse,
+    AuthUser,
+    LoginRequest,
+    RefreshRequest,
+    SignupRequest,
+)
+from v1.auth.service import AuthService, AuthServiceGateway
+
+
+class FakeGateway(AuthServiceGateway):
+    def __init__(self, response: AuthTokenResponse) -> None:
+        self._response = response
+
+    async def signup(self, request: SignupRequest) -> AuthTokenResponse:
+        return self._response
+
+    async def login(self, request: LoginRequest) -> AuthTokenResponse:
+        return self._response
+
+    async def refresh(self, request: RefreshRequest) -> AuthTokenResponse:
+        return self._response
+
+    async def logout(self, refresh_token: str | None) -> None:
+        return None
+
+
+@pytest.mark.asyncio
+async def test_signup_maps_response() -> None:
+    user = AuthUser(id="user-1", email="user@example.com")
+    token_response = AuthTokenResponse(
+        access_token="access",
+        refresh_token="refresh",
+        expires_in=3600,
+        token_type="bearer",
+        user=user,
+    )
+    service = AuthService(gateway=FakeGateway(token_response))
+
+    result = await service.signup(
+        SignupRequest(email="user@example.com", password="secret123")
+    )
+
+    assert result.access_token == "access"
+    assert result.refresh_token == "refresh"
+    assert result.user.id == "user-1"
+
+
+class LogoutAssertingGateway(AuthServiceGateway):
+    def __init__(self, expected_refresh_token: str) -> None:
+        self._expected_refresh_token = expected_refresh_token
+
+    async def signup(self, request: SignupRequest) -> AuthTokenResponse:
+        raise NotImplementedError
+
+    async def login(self, request: LoginRequest) -> AuthTokenResponse:
+        raise NotImplementedError
+
+    async def refresh(self, request: RefreshRequest) -> AuthTokenResponse:
+        raise NotImplementedError
+
+    async def logout(self, refresh_token: str | None) -> None:
+        assert refresh_token == self._expected_refresh_token
+
+
+@pytest.mark.asyncio
+async def test_logout_forwards_refresh_token() -> None:
+    service = AuthService(gateway=LogoutAssertingGateway("refresh-token"))
+
+    await service.logout("refresh-token")