Fix Codex upgrade script edge cases

scripts/start-codex-app-server

@@ -42,7 +42,9 @@ USAGE
 }
 
 pid_from_file() {
+  if [[ -f "$PID_FILE" ]]; then
     tr -cd '0-9' < "$PID_FILE" 2>/dev/null || true
+  fi
 }
 
 server_pid() {
@@ -349,7 +351,10 @@ extract_codex_binary() {
   tar -xzf "$archive" -C "$dest/extract"
   found="$(find "$dest/extract" -type f -name codex -print | head -n 1)"
   if [[ -z "$found" ]]; then
-    echo "downloaded archive does not contain a codex binary" >&2
+    found="$(find "$dest/extract" -type f -name 'codex-*' -perm -u+x -print | head -n 1)"
+  fi
+  if [[ -z "$found" ]]; then
+    echo "downloaded archive does not contain a Codex executable" >&2
     return 1
   fi
   chmod +x "$found"