Add Jina Reader API fallback for web crawling

Jsoup fails on bot-blocked sites (403). Now tries Jsoup first,
then falls back to Jina Reader (r.jina.ai) for better coverage.
Supports optional API key via JINA_READER_API_KEY env var.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sundol-backend/src/main/resources/application.yml

@@ -29,6 +29,10 @@ oci:
     model: ${OCI_GENAI_MODEL:google.gemini-2.5-flash}
     base-url: ${OCI_GENAI_BASE_URL:https://inference.generativeai.us-chicago-1.oci.oraclecloud.com/20231130/actions}
 
+jina:
+  reader:
+    api-key: ${JINA_READER_API_KEY:}
+
 logging:
   level:
     com.sundol: DEBUG