fix(tests): repair test regressions from zod v3 downgrade

- Fix zod/v4 imports in background-task schema tests
- Remove ZWSP prefix from agent-key-remapper test (fixed in #3136)
- Use toMatchObject for openai-only catalog tests (fallback_models added by #3144)
- Replace z.toJSONSchema (zod v4) with zodToJsonSchema (zod v3 compat)
- Fix task-list.ts type narrowing for zod v3 inferred types

script/build-schema-document.ts

@@ -1,10 +1,10 @@
-import * as z from "zod"
+import { zodToJsonSchema } from "zod-to-json-schema"
 import { OhMyOpenCodeConfigSchema } from "../src/config/schema"
 
 export function createOhMyOpenCodeJsonSchema(): Record<string, unknown> {
-  const jsonSchema = z.toJSONSchema(OhMyOpenCodeConfigSchema, {
-    target: "draft-7",
-    unrepresentable: "any",
+  const jsonSchema = zodToJsonSchema(OhMyOpenCodeConfigSchema, {
+    target: "jsonSchema7",
+    $refStrategy: "none",
   })
 
   return {