test(perf): add macOS Tauri WebView performance harness

Drive the production home traffic graph through embedded WebDriver in an
isolated optimized measurement build. Record attributed WebContent and main
process CPU/RSS distributions across foreground, hidden and restored phases.

Keep replay, raw reports, independent-run comparison, cleanup checks and
focused validation available through project commands. Normal release builds
exclude the automation service and measurement entry points.

src-tauri/src/main.rs

@@ -1,10 +1,19 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
-use std::{
-    process::ExitCode,
-    sync::atomic::{AtomicUsize, Ordering},
-};
+use std::process::ExitCode;
+#[cfg(not(all(feature = "perf-harness", target_os = "macos")))]
+use std::sync::atomic::{AtomicUsize, Ordering};
 
+#[cfg(all(feature = "perf-harness", target_os = "macos"))]
+#[path = "../../scripts/perf/app.rs"]
+mod perf;
+
+#[cfg(all(feature = "perf-harness", target_os = "macos"))]
+fn main() -> ExitCode {
+    perf::run()
+}
+
+#[cfg(not(all(feature = "perf-harness", target_os = "macos")))]
 fn main() -> ExitCode {
     let default_parallelism = std::thread::available_parallelism().map(|n| n.get()).unwrap_or(1);
     let worker_limit = std::cmp::min(default_parallelism, 8);