web: 'opencode web' crashes on headless Linux (ENOENT: xdg-open not found)

Bug

Running opencode web on a headless Linux environment (e.g. a GitHub Codespace / container without a desktop) starts the server, prints the banner, then crashes because it tries to auto-open a browser via xdg-open, which does not exist in the container.

Repro

In a mcr.microsoft.com/devcontainers/base:ubuntu codespace (no xdg-utils installed):

$ opencode web --port 3000 --hostname 0.0.0.0
!  OPENCODE_SERVER_PASSWORD is not set; server is unsecured.

  █▀▀█ █▀▀█ █▀▀█ █▀▀▄ █▀▀▀ █▀▀█ █▀▀█ █▀▀█
  █  █ █  █ █▀▀▀ █  █ █    █  █ █  █ █▀▀▀
  ▀▀▀▀ █▀▀▀ ▀▀▀▀ ▀  ▀ ▀▀▀▀ ▀▀▀▀ ▀▀▀▀ ▀▀▀▀

  Local access:       http://localhost:3000
  Network access:     http://10.0.0.99:3000
error: Executable not found in $PATH: "xdg-open"
      path: "xdg-open",
     errno: -2,
   syscall: "spawn xdg-open",
 spawnargs: [ "http://localhost:3000" ],
      code: "ENOENT"

The whole process exits (exit code 1), taking the web server down with it. The server itself started fine (port responds 200 before the crash).

Expected

• The server should keep running; opening a browser is a convenience, not a requirement.
• In headless environments (no DISPLAY/WAYLAND_DISPLAY, or no xdg-open binary), it should skip auto-open gracefully (log a warning) instead of crashing.
• Bonus: a --no-open/--dont-open flag would help scripts/containers.

Workaround (current)

Install xdg-utils in the container (apt-get install -y xdg-utils) so xdg-open exists.

Env

• opencode 1.18.31 (also affects latest)
• Ubuntu 24.04 devcontainer, headless