fix(clippy): use is_none_or instead of map_or for Option check

is_none_or is stable since Rust 1.82 and preferred by clippy over
map_or(true, ...) pattern.

https://claude.ai/code/session_012nbbEyFXjDwdZZrHg7gFNK

src/agent/agent_loop.rs

@@ -1151,7 +1151,7 @@ impl Agent {
                 .await;
             let mut sess = session.lock().await;
             if let Some(thread) = sess.threads.get(&target_thread_id) {
-                let authorized = thread.source_channel.as_ref().map_or(true, |src| {
+                let authorized = thread.source_channel.as_ref().is_none_or(|src| {
                     src == &message.channel
                         || message.channel == "web"
                         || message.channel == "gateway"