若干更新迭代

contracts/http/route-surface.v1.json

@@ -34,6 +34,7 @@
     { "method": "POST", "path": "/api/auth/password" },
     { "method": "POST", "path": "/api/auth/password/change" },
     { "method": "GET", "path": "/api/billing" },
+    { "method": "GET", "path": "/api/billing/balance" },
     { "method": "POST", "path": "/api/billing/quote" },
     { "method": "GET", "path": "/api/generations/image" },
     { "method": "POST", "path": "/api/generations/image" },