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/bridge/mod.rs

@@ -87,20 +87,15 @@ impl BridgeResource {
 /// Inserted by BridgePlugin as Pending. Set to Complete in main.rs after
 /// `send_handshake()` succeeds. `receive_bridge_inputs` logs a warning
 /// if inputs arrive while still Pending.
-#[derive(Resource, Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Resource, Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub enum HandshakeState {
     /// Handshake not yet sent. Inputs arriving in this state trigger a warning.
+    #[default]
     Pending,
     /// Handshake sent. Normal operation.
     Complete,
 }
 
-impl Default for HandshakeState {
-    fn default() -> Self {
-        Self::Pending
-    }
-}
-
 /// Receive inputs from bridge and push to InputQueue.
 /// Protocol errors (malformed input) are recoverable: the frame is skipped
 /// and a SimError is pushed to the SimErrorBuffer for client reporting (#85).