feat: add canonical URL handling and entity quality checks

- Implemented canonical URL strategies for city-specific domains and entities.
- Added helper functions for domain and city resolution.
- Created tests for canonical URL generation and domain resolution.
- Introduced entity quality checks for doctors and clinics to ensure meaningful content.
- Developed unique introductory texts for listing pages to avoid duplicate content.
- Established robots.txt policies for listing pages to manage indexing based on user filters.
- Enhanced specialty content with dynamic introductions and FAQs to improve SEO.

app/blogs/page.js

@@ -11,8 +11,8 @@ export async function generateMetadata() {
   return {
     title,
     description,
-    // مقالات روی همه‌ی دامنه‌ها یکسان‌اند — تجمیع روی دامنه‌ی اصلی
-    alternates: { canonical: "https://nobat724.com/blogs" },
+    // C1-a — لیست بلاگ per-domain است (پست‌های همان شهر + سراسری)؛
+    // canonical لایهٔ layout (self روی همان دامنه) درست است.
     openGraph: { title, description, images: [image] },
     twitter: { card: "summary_large_image", title, description, images: [image] },
   };