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>

lib/content/zhouyi.ts

@@ -1,13 +1,54 @@
 import fs from "fs/promises";
 import path from "path";
 
-const CONTENT_ROOT = path.join(process.cwd(), "content", "zhouyi", "docs");
+const DOCS_ROOT = path.join(process.cwd(), "content", "zhouyi", "docs");
+const OTHER_ROOT = path.join(DOCS_ROOT, "other");
+
+export type LearnVariant = "traditional" | "simplified";
+
+function getVariantRoot(variant: LearnVariant): string {
+  return variant === "traditional" ? DOCS_ROOT : OTHER_ROOT;
+}
+
+export async function listGuaMarks(
+  variant: LearnVariant = "traditional",
+): Promise<string[]> {
+  const dir = getVariantRoot(variant);
+  const entries = await fs.readdir(dir, { withFileTypes: true });
+  return entries
+    .filter((entry) => entry.isDirectory() && /^\d{2}\./.test(entry.name))
+    .map((entry) => entry.name)
+    .sort();
+}
 
 export async function readGuaMarkdown(guaMark: string): Promise<string> {
-  const filePath = path.join(CONTENT_ROOT, guaMark, "index.md");
+  const filePath = path.join(DOCS_ROOT, guaMark, "index.md");
   return fs.readFile(filePath, "utf-8");
 }
 
+export async function readLearnMarkdown(
+  guaMark: string,
+  variant: LearnVariant = "traditional",
+): Promise<string> {
+  const root = getVariantRoot(variant);
+  const filePath =
+    guaMark === "index"
+      ? path.join(root, "index.md")
+      : path.join(root, guaMark, "index.md");
+  return fs.readFile(filePath, "utf-8");
+}
+
+export function stripFrontmatter(content: string): string {
+  if (!content.startsWith("---")) {
+    return content;
+  }
+  const end = content.indexOf("---", 3);
+  if (end === -1) {
+    return content;
+  }
+  return content.slice(end + 3).trimStart();
+}
+
 export function extractZhangMingRen(guaDetail: string): string | undefined {
   return guaDetail
     .match(/(\*\*台灣張銘仁[\s\S]*?)(?=周易第\d+卦)/)?.[1]
@@ -39,3 +80,11 @@ export function extractChangeDetails(
 
   return changeList;
 }
+
+export function getGuaNumber(guaMark: string): number {
+  return parseInt(guaMark.split(".")[0], 10);
+}
+
+export function getGuaName(guaMark: string): string {
+  return guaMark.split(".").slice(1).join(".");
+}