fix: send auth token with sentence boundary API requests

ios/OralTrainer/Services/HTTPClient.swift

@@ -25,14 +25,17 @@ enum HTTPClient {
         _ type: T.Type,
         baseURL: String,
         path: String,
-        timeout: TimeInterval
+        timeout: TimeInterval,
+        additionalHeaders: [String: String] = [:]
     ) async throws -> (value: T, effectiveBaseURL: String) {
+        var headers = ["Accept": "application/json"]
+        headers.merge(additionalHeaders) { _, new in new }
         let result = try await execute(
             baseURL: baseURL,
             path: path,
             method: "GET",
             timeout: timeout,
-            headers: ["Accept": "application/json"]
+            headers: headers
         )
         guard (200...299).contains(result.statusCode) else {
             let body = String(data: result.body, encoding: .utf8) ?? ""