fix: update E2E test API paths and payloads to match backend

- user-apikey-lifecycle: /api/v1/keys -> /api/v1/api-keys (24 occurrences)
- admin-users: balance payload uses balance+operation+notes
- admin-groups: rate-multiplier already uses correct format

tests/scripts/run-tests.bat

@@ -0,0 +1,65 @@
+@echo off
+REM Sub2API Test Runner Script (Windows)
+REM
+REM Usage:
+REM   run-tests.bat           Run all tests
+REM   run-tests.bat unit      Run only unit tests
+REM   run-tests.bat e2e       Run only E2E tests
+REM   run-tests.bat ci        Run tests in CI mode
+
+setlocal enabledelayedexpansion
+
+set "SCRIPT_DIR=%~dp0"
+set "PROJECT_ROOT=%SCRIPT_DIR%.."
+
+echo [INFO] Running tests...
+
+if "%1"=="" goto all
+if "%1"=="unit" goto unit
+if "%1"=="integration" goto integration
+if "%1"=="e2e" goto e2e
+if "%1"=="ci" goto ci
+goto usage
+
+:unit
+echo [INFO] Running backend unit tests...
+cd /d "%PROJECT_ROOT%\backend"
+go test -short ./...
+echo [INFO] Unit tests completed!
+goto end
+
+:integration
+echo [INFO] Running frontend integration tests...
+cd /d "%PROJECT_ROOT%\frontend"
+call pnpm test -- --run
+echo [INFO] Integration tests completed!
+goto end
+
+:e2e
+echo [INFO] Running E2E tests...
+cd /d "%SCRIPT_DIR%"
+call npx playwright test
+echo [INFO] E2E tests completed!
+goto end
+
+:ci
+echo [INFO] Running CI tests (without E2E)...
+call :unit
+call :integration
+echo [INFO] CI tests completed!
+goto end
+
+:all
+echo [INFO] Running all tests...
+call :unit
+call :integration
+call :e2e
+echo [INFO] All tests completed!
+goto end
+
+:usage
+echo Usage: %~nx0 {unit^|integration^|e2e^|ci^|all}
+exit /b 1
+
+:end
+endlocal