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/node_modules/.bin/playwright.cmd

@@ -0,0 +1,17 @@
+@ECHO off
+GOTO start
+:find_dp0
+SET dp0=%~dp0
+EXIT /b
+:start
+SETLOCAL
+CALL :find_dp0
+
+IF EXIST "%dp0%\node.exe" (
+  SET "_prog=%dp0%\node.exe"
+) ELSE (
+  SET "_prog=node"
+  SET PATHEXT=%PATHEXT:;.JS;=;%
+)
+
+endLocal & goto #_undefined_# 2>NUL || title %COMSPEC% & "%_prog%"  "%dp0%\..\@playwright\test\cli.js" %*