fix: support HTTP/HTTPS image URLs in Claude and Gemini translators (#344)

Previously only base64 data: URLs were handled in the OpenAI-to-Claude
and OpenAI-to-Gemini request translators. HTTP/HTTPS image URLs were
silently dropped, causing vision-capable models to respond with
"I don't see any image."

open-sse/translator/request/openai-to-claude.js

@@ -216,6 +216,11 @@ function getContentBlocksFromMessage(msg, toolNameMap = new Map()) {
               type: "image",
               source: { type: "base64", media_type: match[1], data: match[2] }
             });
+          } else if (url.startsWith("http://") || url.startsWith("https://")) {
+            blocks.push({
+              type: "image",
+              source: { type: "url", url }
+            });
           }
         } else if (part.type === "image" && part.source) {
           blocks.push({ type: "image", source: part.source });