feat(i18n): add ui locale runtime

tests/i18n-catalog.mjs

@@ -0,0 +1,47 @@
+import assert from "node:assert/strict";
+
+import zhCN from "../i18n/zh-CN.js";
+import enUS from "../i18n/en-US.js";
+
+function catalogKeys(catalog) {
+  return Object.keys(catalog).sort();
+}
+
+function extractInterpolationParams(template) {
+  const params = new Set();
+  const re = /\{\{?\s*([A-Za-z_][\w.-]*)\s*\}?\}/g;
+  let match;
+  while ((match = re.exec(String(template)))) {
+    params.add(match[1]);
+  }
+  return [...params].sort();
+}
+
+const zhKeys = catalogKeys(zhCN);
+const enKeys = catalogKeys(enUS);
+const onlyZh = zhKeys.filter((key) => !Object.prototype.hasOwnProperty.call(enUS, key));
+const onlyEn = enKeys.filter((key) => !Object.prototype.hasOwnProperty.call(zhCN, key));
+
+assert.deepEqual(onlyZh, [], `keys in zh-CN but missing in en-US: ${onlyZh.join(", ")}`);
+assert.deepEqual(onlyEn, [], `keys in en-US but missing in zh-CN: ${onlyEn.join(", ")}`);
+assert.equal(zhKeys.length, enKeys.length, "zh-CN and en-US catalog key counts differ");
+
+for (const key of zhKeys) {
+  assert.equal(typeof zhCN[key], "string", `zh-CN ${key} must be a string`);
+  assert.equal(typeof enUS[key], "string", `en-US ${key} must be a string`);
+  assert.ok(zhCN[key].trim(), `zh-CN ${key} must not be empty`);
+  assert.ok(enUS[key].trim(), `en-US ${key} must not be empty`);
+  assert.deepEqual(
+    extractInterpolationParams(zhCN[key]),
+    extractInterpolationParams(enUS[key]),
+    `interpolation params differ for ${key}`,
+  );
+}
+
+assert.ok(zhKeys.length >= 60, "Phase 0 catalog should include a meaningful seed set");
+assert.ok(
+  zhKeys.some((key) => extractInterpolationParams(zhCN[key]).length > 0),
+  "catalog should include at least one interpolated string",
+);
+
+console.log("i18n catalog tests passed");