feat(i18n): 21-language pipeline, landing/docs/API wiring, landing+API translations

Shared Claude Code translation pipeline (scripts/i18n, no API key) plus Astro/VitePress/Scalar i18n wiring. Landing and API reference translated into all 20 languages; docs i18n wiring + English source anchors. The translated docs markdown (apps/docs/<locale>/**, 3,620 files) follows in a companion PR because it exceeds GitHub's per-PR CI file limit.

scripts/i18n/lib/shared-i18n.mjs

@@ -0,0 +1,30 @@
+// scripts/i18n/lib/shared-i18n.mjs
+import { SUPPORTED_LOCALES } from "../../../packages/shared/src/i18n/index.ts";
+
+/** @returns {string[]} all supported locale codes */
+export function localeCodes() {
+  return SUPPORTED_LOCALES.map((l) => l.code);
+}
+
+/**
+ * The exported const name inside a locale file is the code camel-cased:
+ * "de" -> "de", "pt-BR" -> "ptBR", "zh-CN" -> "zhCN".
+ * @param {string} code
+ * @returns {string}
+ */
+function exportName(code) {
+  return code.replace(/-([a-z])/gi, (_m, c) => c.toUpperCase());
+}
+
+/**
+ * Load the translated `tools` namespace for a locale:
+ * { [toolId]: { name, description } }.
+ * @param {string} code
+ * @returns {Promise<Record<string, { name: string, description: string }>>}
+ */
+export async function loadToolStrings(code) {
+  const mod = await import(`../../../packages/shared/src/i18n/${code}.ts`);
+  const dict = mod[exportName(code)];
+  if (!dict?.tools) throw new Error(`No tools namespace in locale ${code}`);
+  return dict.tools;
+}