Fix anomaly detection issues and add missing functionality

Fixed issues:
- Corrected Welford's online algorithm for variance calculation
- Added NaN and infinity guards to prevent invalid calculations
- Added Serialize/Deserialize traits to AnomalyScore and ProcessProfile

Added functionality:
- Profile persistence with save_profiles() and load_profiles()
- Global baseline computation from all process profiles
- Profile cleanup method to remove stale profiles
- Additional utility methods for profile management

ghost-core/tests/macos_process_test.rs

@@ -0,0 +1,45 @@
+#[cfg(target_os = "macos")]
+#[test]
+fn test_macos_process_enumeration() {
+    use ghost_core::process;
+
+    let processes = process::enumerate_processes().expect("Failed to enumerate processes");
+
+    assert!(!processes.is_empty(), "Should find at least some processes");
+
+    println!("Found {} processes", processes.len());
+
+    for proc in processes.iter().filter(|p| p.pid > 0).take(5) {
+        println!("PID: {}, Name: {}, Path: {:?}", proc.pid, proc.name, proc.path);
+        assert!(proc.pid > 0, "PID should be positive");
+        assert!(!proc.name.is_empty(), "Process name should not be empty");
+    }
+
+    let current_pid = std::process::id();
+    let current_process = processes.iter().find(|p| p.pid == current_pid);
+
+    if let Some(proc) = current_process {
+        println!("Current process found: PID={}, Name={}", proc.pid, proc.name);
+    } else {
+        println!("Current process (PID={}) not in list - this is OK for test processes", current_pid);
+    }
+
+    assert!(processes.iter().any(|p| p.pid == 1), "Should at least find launchd (PID 1)");
+}
+
+#[cfg(target_os = "macos")]
+#[test]
+fn test_process_info_structure() {
+    use ghost_core::process;
+
+    let processes = process::enumerate_processes().expect("Failed to enumerate processes");
+
+    for proc in processes.iter().take(10) {
+        assert!(proc.pid > 0 || proc.pid == 0);
+        assert!(proc.thread_count >= 1);
+
+        if proc.pid > 0 {
+            assert!(!proc.name.is_empty() || proc.name.starts_with("pid_"));
+        }
+    }
+}