fix(channels): check response status in send() for Telegram, Slack, and Discord

Reliability fix: check HTTP response status in channel send methods

src/util.rs

@@ -1,4 +1,4 @@
-//! Utility functions for ZeroClaw.
+//! Utility functions for `ZeroClaw`.
 //!
 //! This module contains reusable helper functions used across the codebase.
 
@@ -58,7 +58,10 @@ mod tests {
     fn test_truncate_ascii_with_truncation() {
         // ASCII string longer than limit - truncates
         assert_eq!(truncate_with_ellipsis("hello world", 5), "hello...");
-        assert_eq!(truncate_with_ellipsis("This is a long message", 10), "This is a...");
+        assert_eq!(
+            truncate_with_ellipsis("This is a long message", 10),
+            "This is a..."
+        );
     }
 
     #[test]