[FEATURE]: Desktop app should display visible error notification on startup failure #37223

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

When the OpenCode desktop app encounters an error during startup (e.g., dependency install failure, config parse error), it currently plays a Windows system error sound with no visible error message, toast, or dialog. Users have no way to know what went wrong without manually digging through log files at %APPDATA%\ai.opencode.desktop\logs\ or %USERPROFILE%.local\share\opencode\log\opencode.log.
I request that the desktop app display an in-app error notification (toast or dialog) containing the actual error message when a startup error occurs, so users can self-diagnose without needing to find log files manually. This should include errors like:

• Background dependency install failure (npm install)
• Config file parse errors
• Plugin load failures
• MCP server connection failures
  All these currently produce a silent error sound with no user-facing explanation.