Fix AI streaming, learn images, and full city regions.

Remove use server from stream helper to fix RSC errors; support OPENAI_API_BASE alias; render HTML tables via rehype-raw with gua-image API; expand regions to 356 prefecture-level cities.

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

app/learn/[slug]/page.tsx

@@ -61,7 +61,7 @@ export default async function GuaDetailPage({
       <div className="mb-4 text-sm text-muted-foreground">
         第 {getGuaNumber(guaMark)} 卦 · {getGuaName(guaMark)}
       </div>
-      <MarkdownContent content={content} variant="traditional" />
+      <MarkdownContent content={content} variant="traditional" guaMark={guaMark} />
       <GuaFooter guaMark={guaMark} guaNum={num} />
     </PageShell>
   );

app/learn/other/[slug]/page.tsx

@@ -57,7 +57,7 @@ export default async function GuaOtherDetailPage({
       <div className="mb-4 text-sm text-muted-foreground">
         第 {getGuaNumber(guaMark)} 卦 · {getGuaName(guaMark)}
       </div>
-      <MarkdownContent content={content} variant="simplified" />
+      <MarkdownContent content={content} variant="simplified" guaMark={guaMark} />
       <GuaFooter guaMark={guaMark} guaNum={guaNumFromMark(guaMark)} />
     </PageShell>
   );