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/tests/ipc_bench.rs

@@ -102,11 +102,9 @@ fn ipc_round_trip_latency() {
     let handshake: HandshakeMessage =
         rmp_serde::from_slice(&handshake_bytes).expect("deserialize HandshakeMessage");
     assert_eq!(
-        handshake.protocol_version,
-        PROTOCOL_VERSION,
+        handshake.protocol_version, PROTOCOL_VERSION,
         "handshake version mismatch: server={}, client={}",
-        handshake.protocol_version,
-        PROTOCOL_VERSION
+        handshake.protocol_version, PROTOCOL_VERSION
     );
 
     let make_input = |tick: u64| PlayerInput {