feat: complete remaining Go backend modules

tests/providers-contract.test.ts

@@ -0,0 +1,3 @@
+import { readFile } from "node:fs/promises";
+import { describe, expect, it } from "vitest";
+describe("Go provider adapter contract",()=>{it("freezes bounded adapters and safe errors",async()=>{const c=JSON.parse(await readFile(new URL("../contracts/providers/http-v1.json",import.meta.url),"utf8"));expect(Object.keys(c.providers)).toEqual(["volcengine-visual","evolink","bailian","seedance","mock"]);expect(c.errors).toEqual({generic:true,secretSafe:true});expect(c.liveCallsInTests).toBe(false);});});