fix: reap zombie Chrome process and fast-detect crash for auto-restart (#1023)

When Chrome crashes (e.g. SIGTRAP from CHECK() assertion), the daemon
now:

1. Reaps the zombie immediately via a SIGCHLD handler in the event loop
   that calls waitpid(-1, WNOHANG)
2. Detects the crash instantly on the next command via a non-blocking
   try_wait() check (has_process_exited), avoiding the 3-second CDP
   timeout that is_connection_alive() would incur
3. Auto-relaunches Chrome transparently for the caller

Fixes #1017

Co-authored-by: ctate <366502+ctate@users.noreply.github.com>

cli/src/native/cdp/chrome.rs

@@ -17,6 +17,17 @@ impl ChromeProcess {
         let _ = self.child.wait();
     }
 
+    /// Returns the OS process ID of the Chrome child process.
+    pub fn id(&self) -> u32 {
+        self.child.id()
+    }
+
+    /// Non-blocking check whether Chrome has exited.
+    /// Returns `true` if the process has exited (and reaps it), `false` if still running.
+    pub fn has_exited(&mut self) -> bool {
+        matches!(self.child.try_wait(), Ok(Some(_)) | Err(_))
+    }
+
     /// Wait for Chrome to exit on its own (after Browser.close CDP command),
     /// falling back to kill() if it doesn't exit within the timeout.
     /// This allows Chrome to flush cookies and other state to the user-data-dir.