test(tail): retire stale i18n __MISSING__ repro + fix qianfan website URL

Base-red slice 6, rebased onto the advanced release/v3.8.49 (91fd5f9). The oauth
grok-cli #7610 guard was already fixed on the base by #8027 (it reads the warning
from grokCliAuthJson.ts) — dropped from this slice to avoid a conflicting duplicate.
Remaining two, still red on the current base:

- i18n #7258: the "focused repro" asserted zh-TW.json STILL carries raw __MISSING__:
  placeholders. That backlog was filled (the "no locale has a raw __MISSING__: leaf"
  invariant is the durable guard); retired the now-inverted repro.
- qianfan: Baidu renamed the product page (product/wenxinworkshop -> product-s/
  qianfan_home); updated the expected website URL.

Validated (clean env): i18n 4/0, qianfan 5/0; oauth-modal-grok 2/0 already green on base.

tests/unit/i18n-missing-placeholder-fallback.test.ts

@@ -29,11 +29,7 @@ function loadLocale(locale: string): Record<string, unknown> {
   return JSON.parse(raw) as Record<string, unknown>;
 }
 
-function collectPlaceholderLeaves(
-  node: unknown,
-  pathPrefix: string,
-  out: string[]
-): void {
+function collectPlaceholderLeaves(node: unknown, pathPrefix: string, out: string[]): void {
   if (node === null || typeof node !== "object") {
     if (typeof node === "string" && node.startsWith(PLACEHOLDER_PREFIX)) {
       out.push(pathPrefix);
@@ -47,19 +43,13 @@ function collectPlaceholderLeaves(
 }
 
 // ---------------------------------------------------------------------------
-// 1. Focused repro: the exact keys from the issue report
+// 1. (Retired) The original repro asserted zh-TW.json STILL carried raw
+// __MISSING__: placeholders. That translation backlog has since been filled, so
+// the sentinel no longer ships on disk — the invariant "no locale has a raw
+// __MISSING__: leaf" (test 3 below) is the durable guard. Keeping a test that
+// requires the backlog to EXIST would fail exactly when the content is healthy.
 // ---------------------------------------------------------------------------
 
-test("#7258 repro: zh-TW keys carry a raw __MISSING__: placeholder before the fix is exercised", () => {
-  const zhTW = loadLocale("zh-TW");
-  const leaves: string[] = [];
-  collectPlaceholderLeaves(zhTW, "", leaves);
-  assert.ok(
-    leaves.length > 0,
-    "expected zh-TW.json to still contain __MISSING__: placeholders (translation content backlog)"
-  );
-});
-
 test("#7258: deepMergeFallback replaces an untranslated __MISSING__ placeholder with the EN fallback value", () => {
   const target: Record<string, unknown> = {
     localUsageCommand: `${PLACEHOLDER_PREFIX}Run this command locally`,

tests/unit/qianfan-provider.test.ts

@@ -26,7 +26,7 @@ test("qianfan registers Baidu ERNIE as an OpenAI-compatible API key provider", (
 
   assert.ok(APIKEY_PROVIDERS.qianfan, "qianfan should be visible in API key providers");
   assert.equal(APIKEY_PROVIDERS.qianfan.name, "Baidu Qianfan");
-  assert.equal(APIKEY_PROVIDERS.qianfan.website, "https://cloud.baidu.com/product/wenxinworkshop");
+  assert.equal(APIKEY_PROVIDERS.qianfan.website, "https://cloud.baidu.com/product-s/qianfan_home");
   assert.equal(APIKEY_PROVIDERS.qianfan.passthroughModels, undefined);
 
   assert.equal(PROVIDERS.qianfan.baseUrl, registryEntry.baseUrl);