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/hardware.rs

@@ -115,14 +115,20 @@ pub fn probe_hardware(mode: Option<ResourceMode>) -> HardwareProbe {
                 tracing::warn!("GPU mode set but VRAM probe failed — falling back to system RAM");
                 let mut sys = System::new_all();
                 sys.refresh_memory();
-                (sys.total_memory() / (1024 * 1024), sys.available_memory() / (1024 * 1024))
+                (
+                    sys.total_memory() / (1024 * 1024),
+                    sys.available_memory() / (1024 * 1024),
+                )
             }
         }
         _ => {
             // CPU mode or Apple Silicon (unified memory = system RAM)
             let mut sys = System::new_all();
             sys.refresh_memory();
-            (sys.total_memory() / (1024 * 1024), sys.available_memory() / (1024 * 1024))
+            (
+                sys.total_memory() / (1024 * 1024),
+                sys.available_memory() / (1024 * 1024),
+            )
         }
     };
 
@@ -228,7 +234,10 @@ pub enum ScalingDecision {
 /// Returns (total_mb, free_mb) for the first GPU, or None.
 fn probe_nvidia_vram() -> Option<(u64, u64)> {
     let output = Command::new("nvidia-smi")
-        .args(["--query-gpu=memory.total,memory.free", "--format=csv,noheader,nounits"])
+        .args([
+            "--query-gpu=memory.total,memory.free",
+            "--format=csv,noheader,nounits",
+        ])
         .output()
         .ok()?;
 
@@ -480,9 +489,9 @@ mod tests {
     fn evaluate_scaling_hold_when_calm() {
         let decision = evaluate_scaling(
             ResourceMode::Cpu,
-            2,   // running
-            5,   // queue depth (low)
-            1,   // active
+            2, // running
+            5, // queue depth (low)
+            1, // active
             None,
         );
         assert!(matches!(decision, ScalingDecision::Hold));