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

@@ -0,0 +1,16 @@
+#!/bin/sh
+basedir=$(dirname "$(echo "$0" | sed -e 's,\\,/,g')")
+
+case `uname` in
+    *CYGWIN*|*MINGW*|*MSYS*)
+        if command -v cygpath > /dev/null 2>&1; then
+            basedir=`cygpath -w "$basedir"`
+        fi
+    ;;
+esac
+
+if [ -x "$basedir/node" ]; then
+  exec "$basedir/node"  "$basedir/../@playwright/test/cli.js" "$@"
+else 
+  exec node  "$basedir/../@playwright/test/cli.js" "$@"
+fi