Add conditional User-Agent header to API requests

- Modified the `apiRequestWithHeaders` function to include a User-Agent header titled "cyber-circle-creator" for outgoing fetch requests.
- Implemented retry logic to handle network errors by resending requests without the User-Agent if the initial request fails.

js/create-circle.js

@@ -1,3 +1,8 @@
+/**
+ *
+ * @param {RequestInfo | URL} url
+ * @param {{ body?: any } & RequestInit?} options
+ */
 /**
  *
  * @param {RequestInfo | URL} url
@@ -6,6 +11,12 @@
 async function apiRequestWithHeaders(url, options = null) {
     console.log(`Fetching :: ${url}`);
 
+    // Old version
+    // -----------------
+    // I left the old version in here in case there are any problems.
+    // The version with user-agent is still very experimental.
+
+    /*
     if (options && options.body) {
         options.body = JSON.stringify(options.body);
     }
@@ -26,6 +37,46 @@ async function apiRequestWithHeaders(url, options = null) {
                 error: `Error fetching ${url}: ${error}`
             };
         });
+    */
+
+    // New version with user-agent "cyber-circle-creator"
+    const defaultUserAgent = { 'User-Agent': 'cyber-circle-creator' };
+    
+    // Merge headers
+    options = options || {};
+    options.headers = { ...(options.headers || {}), ...defaultUserAgent };
+
+    if (options.body) {
+        options.body = JSON.stringify(options.body);
+    }
+
+    try {
+        const response = await fetch(url, options);
+        
+        if (response.ok) {
+            return { response: { headers: response.headers, body: await response.json(), error: undefined }};
+        }
+
+        throw new Error(`Error fetching ${url}: ${response.status} ${response.statusText}`);
+    } catch (error) {
+        console.error(`Error fetching with User-Agent "cyber-circle":`, error);
+        
+        try {
+            const fallbackResponse = await fetch(url, { ...(options ?? {}), headers: undefined });
+            
+            if (fallbackResponse.ok) {
+                return { response: { headers: fallbackResponse.headers, body: await fallbackResponse.json(), error: undefined }};
+            }
+            
+            throw new Error(`Error fetching ${url}: ${fallbackResponse.status} ${fallbackResponse.statusText}`);
+        } catch (fallbackError) {
+            console.error(`Fallback fetching without User-Agent failed:`, fallbackError);
+            return {
+                response: undefined,
+                error: `Error fetching ${url}: ${fallbackError}`
+            };
+        }
+    }
 }
 
 /**