Fix learn 404, coin animation, full regions, and AI key errors.

Use numeric /learn/{num} routes, register Tailwind coin animations with方孔铜钱 UI, expand to 34 provinces, and surface missing OPENAI_API_KEY clearly.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/learn/gua-footer.tsx

@@ -1,12 +1,20 @@
 import Link from "next/link";
 import { Button } from "@/components/ui/button";
 import { Sparkles } from "lucide-react";
+import { guaNumFromMark } from "@/lib/content/zhouyi";
 
-export default function GuaFooter({ guaMark }: { guaMark: string }) {
+export default function GuaFooter({
+  guaMark,
+  guaNum,
+}: {
+  guaMark: string;
+  guaNum?: string;
+}) {
+  const num = guaNum ?? guaNumFromMark(guaMark);
   return (
     <div className="mt-8 flex flex-wrap gap-3 border-t pt-6">
       <Button asChild size="sm">
-        <Link href={`/liuyao?gua=${encodeURIComponent(guaMark)}`}>
+        <Link href={`/liuyao?gua=${num}`}>
           <Sparkles size={16} className="mr-1" />
           以此卦起卦
         </Link>