docs: clarify site_details includes navigation links

Updated FRONTEND_INTEGRATION.md to note that /site_details already
includes top_nav_links and footer_links, eliminating the need for
separate /links API calls in most cases.

Also includes user-added tests for locale-prefixed API paths.

Author: etewiah

docs/api/FRONTEND_INTEGRATION.md

@@ -100,7 +100,23 @@ export async function getSharedSiteDetails(Astro: AstroGlobal): Promise<SiteDeta
 
 ## Aggregated Data with `include=`
 
-### Reduce API Calls
+### Important: `/site_details` Already Includes Links
+
+The `/site_details` endpoint already includes navigation links:
+
+```json
+{
+  "company_display_name": "Demo Agency",
+  "top_nav_links": [...],
+  "footer_links": [...],
+  "contact_info": {...},
+  "social_links": {...}
+}
+```
+
+This means **you don't need a separate call to `/links`** in most cases!
+
+### Further Aggregation with `include=`
 
 Instead of 5+ separate calls, use the `include=` parameter:
 

spec/requests/api_public/v1/client_config_includes_spec.rb

@@ -38,6 +38,14 @@
       expect(json["data"]).not_to have_key("site_details")
     end
 
+    it "accepts locale-prefixed path with includes" do
+      host! 'client-config-test.example.com'
+      get "/api_public/v1/en/client-config", params: { include: "translations" }
+      expect(response).to have_http_status(200)
+      json = response.parsed_body
+      expect(json["data"]).to have_key("translations")
+    end
+
     context "with include=links" do
       it "includes links with placement" do
         host! 'client-config-test.example.com'

spec/requests/api_public/v1/properties_spec.rb

@@ -98,6 +98,16 @@
       expect(response).to have_http_status(200)
     end
 
+    it "accepts locale-prefixed path" do
+      host! 'properties-test.example.com'
+      get "/api_public/v1/en/properties", params: { sale_or_rental: "sale" }
+      expect(response).to have_http_status(200)
+      json = response.parsed_body
+      expect(json).to have_key("data")
+      expect(response.headers["Vary"]).to include("Accept-Language")
+      expect(response.headers["Vary"]).to include("X-Website-Slug")
+    end
+
     it "supports sort_by price_asc" do
       host! 'properties-test.example.com'
       get "/api_public/v1/properties", params: { sale_or_rental: "sale", sort_by: "price_asc" }