Implement three divination modes, learn pages, and PM2 deploy on port 3130.

Add liuyao/bazi/combined flows with shared calc and AI infrastructure, 64-gua learn routes, and update Ubuntu PM2 deployment docs for port 3130.

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

components/learn/gua-footer.tsx

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

components/learn/markdown-content.tsx

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+import Link from "next/link";
+import Markdown from "react-markdown";
+import type { LearnVariant } from "@/lib/content/zhouyi";
+
+function resolveLearnHref(
+  href: string | undefined,
+  variant: LearnVariant,
+): string | undefined {
+  if (!href) {
+    return href;
+  }
+  if (href.startsWith("http://") || href.startsWith("https://")) {
+    return href;
+  }
+
+  const base = variant === "traditional" ? "/learn" : "/learn/other";
+
+  if (href === "index.md" || href === "./index.md") {
+    return base;
+  }
+  if (href === "other/index.md") {
+    return "/learn/other";
+  }
+  if (href.endsWith("/index.md")) {
+    const mark = href.replace(/\/index\.md$/, "").replace(/^\.\//, "");
+    if (mark.startsWith("other/")) {
+      return `/learn/other/${mark.slice("other/".length)}`;
+    }
+    return `${base}/${mark}`;
+  }
+  return href;
+}
+
+export default function MarkdownContent({
+  content,
+  variant = "traditional",
+}: {
+  content: string;
+  variant?: LearnVariant;
+}) {
+  return (
+    <Markdown
+      className="prose max-w-none dark:prose-invert prose-headings:scroll-mt-20 prose-a:text-primary"
+      components={{
+        a: ({ href, children, ...props }) => {
+          const resolved = resolveLearnHref(href, variant);
+          if (resolved?.startsWith("/")) {
+            return (
+              <Link href={resolved} {...props}>
+                {children}
+              </Link>
+            );
+          }
+          return (
+            <a href={resolved} {...props}>
+              {children}
+            </a>
+          );
+        },
+        img: ({ src, alt, ...props }) => {
+          if (typeof src === "string" && !src.startsWith("http")) {
+            return (
+              <span className="my-2 block rounded border border-dashed p-4 text-center text-sm text-muted-foreground">
+                [{alt || "卦象图片"}]
+              </span>
+            );
+          }
+          return <img src={src} alt={alt} {...props} />;
+        },
+      }}
+    >
+      {content}
+    </Markdown>
+  );
+}