fix: handle existing user in integration test setup

- Add fallback to login when user registration returns 409 Conflict
- Prevents empty user token error when test user already exists
- Allows integration tests to run reliably across multiple executions
- Test now attempts to log in with existing credentials if registration fails

This fixes the issue where the test would fail if the user
'integrationuser@test.com' already existed from a previous test run.

cmd/server/tests/integration_test.go

@@ -218,6 +218,26 @@ func setupTestSuite(t *testing.T) *TestContext {
 			ctx.UserToken = extractToken(authResp)
 			ctx.UserID = authResp.User.ID
 			t.Logf("Created new user: %s (%s)", authResp.User.Email, authResp.User.Role)
+		} else if resp.StatusCode == http.StatusConflict {
+			// User already exists, log in instead
+			t.Logf("User already exists, attempting login...")
+			loginReq := map[string]interface{}{
+				"login":    "integrationuser@test.com",
+				"password": "UserPass123!",
+			}
+			loginResp := makeRequest(t, "POST", "/api/auth/login", loginReq, "")
+			defer loginResp.Body.Close()
+
+			require.Equal(t, http.StatusOK, loginResp.StatusCode, "Login should succeed for existing user")
+
+			var authResp AuthResponse
+			body, _ := io.ReadAll(loginResp.Body)
+			err := json.Unmarshal(body, &authResp)
+			require.NoError(t, err)
+
+			ctx.UserToken = extractToken(authResp)
+			ctx.UserID = authResp.User.ID
+			t.Logf("Logged in as existing user: %s (%s)", authResp.User.Email, authResp.User.Role)
 		}
 
 		require.NotEmpty(t, ctx.UserToken, "User token is empty")