fix(backend): recursively kill yt-dlp child processes to prevent zombies

src-tauri/src/process.rs

@@ -0,0 +1,26 @@
+use sysinfo::System;
+
+pub fn kill_process_tree(pid: u32) {
+    let mut sys = System::new();
+    sys.refresh_processes(sysinfo::ProcessesToUpdate::All, true);
+    
+    let mut to_kill = vec![sysinfo::Pid::from_u32(pid)];
+    let mut i = 0;
+    while i < to_kill.len() {
+        let current_pid = to_kill[i];
+        for (p, process) in sys.processes() {
+            if process.parent() == Some(current_pid) {
+                if !to_kill.contains(p) {
+                    to_kill.push(*p);
+                }
+            }
+        }
+        i += 1;
+    }
+    
+    for p in to_kill.into_iter().rev() {
+        if let Some(process) = sys.process(p) {
+            process.kill();
+        }
+    }
+}