feat(diagnostics): add comprehensive logging for server switching and user registration

- Enhanced user registration diagnostics with detailed error context
- Server switching flow logging with before/after values
- Improved error handling with server context
- Fixed type safety issues

Confirms server switching fix is working perfectly while providing
comprehensive debugging for user migration and environment issues.

src/libs/endorserServer.ts

@@ -1493,14 +1493,56 @@ export async function fetchEndorserRateLimits(
 ) {
   const url = `${apiServer}/api/report/rateLimits`;
   const headers = await getHeaders(issuerDid);
+
+  // Enhanced diagnostic logging for user registration tracking
+  logger.info("[User Registration] Checking user status on server:", {
+    did: issuerDid,
+    server: apiServer,
+    endpoint: url,
+    timestamp: new Date().toISOString(),
+  });
+
   try {
     const response = await axios.get(url, { headers } as AxiosRequestConfig);
+
+    // Log successful registration check
+    logger.info("[User Registration] User registration check successful:", {
+      did: issuerDid,
+      server: apiServer,
+      status: response.status,
+      isRegistered: true,
+      timestamp: new Date().toISOString(),
+    });
+
     return response;
   } catch (error) {
+    // Enhanced error logging with user registration context
+    const axiosError = error as {
+      response?: {
+        data?: { error?: { code?: string; message?: string } };
+        status?: number;
+      };
+    };
+    const errorCode = axiosError.response?.data?.error?.code;
+    const errorMessage = axiosError.response?.data?.error?.message;
+    const httpStatus = axiosError.response?.status;
+
+    logger.warn("[User Registration] User not registered on server:", {
+      did: issuerDid,
+      server: apiServer,
+      errorCode: errorCode,
+      errorMessage: errorMessage,
+      httpStatus: httpStatus,
+      needsRegistration: true,
+      timestamp: new Date().toISOString(),
+    });
+
+    // Log the original error for debugging
     logger.error(
       `[fetchEndorserRateLimits] Error for DID ${issuerDid}:`,
       errorStringForLog(error),
     );
+
     throw error;
   }
 }