fix(simulation): Clippy cleanup and CI enforcement (#635)

Fix all Clippy warnings across the server codebase (2411 insertions, 1341
deletions). Raise type-complexity-threshold to 750 and too-many-arguments
to 12 in .clippy.toml for idiomatic Bevy ECS system signatures. The server
now passes `cargo clippy -- --deny warnings` cleanly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/voice/queue.rs

@@ -87,6 +87,12 @@ pub struct VoiceQueue {
     paused: Arc<AtomicBool>,
 }
 
+impl Default for VoiceQueue {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl VoiceQueue {
     pub fn new() -> Self {
         let (sender, receiver) = crossbeam_channel::bounded(QUEUE_CAPACITY);