makepad-2.0-troubleshooting

CRITICAL: Use for Makepad 2.0 troubleshooting and common mistakes. Triggers on: makepad error, makepad bug, makepad problem, makepad issue, makepad not working, text invisible, widget not showing, click not working, height zero, makepad pitfall, makepad gotcha, makepad FAQ, makepad help, script_mod error, compile error, widget not found, render not updating, hot reload not working, wasm build error, port conflict, server lock, IME popup, selection handle, popup window crash, canvas splash, POST splash loop, 100% CPU, set_visible not working, on_render empty, event bridge unreliable, float time display, fn tick not called, on_audio not called, button click through, 常见错误, 问题排查, 故障排除, 不显示, 不工作, 看不见, 热重载, 编译错误