feat: YOLO Mode - Skip Permission Prompts

[mguttmann]

Summary

Add a "YOLO Mode" that allows users to skip all permission prompts, similar to Claude Code's --dangerously-skip-permissions flag.

Use Case: Power users who trust OpenCode and want faster workflow without constant permission confirmations.

Proposed Implementation

Backend

• Add OPENCODE_YOLO environment variable flag
• Add yolo: boolean config option in opencode.json
• Modify PermissionNext.ask() to auto-approve when YOLO mode is enabled
• Add runtime state that can be toggled without restart

Server API

• GET /config/yolo - Check current YOLO mode status
• POST /config/yolo - Toggle YOLO mode at runtime

CLI

• Add --yolo or --dangerously-skip-permissions flag
• Example: opencode --yolo or opencode chat --yolo

Desktop App

• Add "Danger Zone" tab in Settings dialog
• Toggle switch with prominent warning:

  Warning: YOLO mode skips ALL permission prompts. OpenCode will execute file changes, bash commands, and other operations without asking for confirmation. Use at your own risk.

Safety Considerations

• Clear warning messaging in both CLI and Desktop
• Not enabled by default
• Session-based (does not persist across restarts unless configured)
• Still respects explicit deny rules in config

Dependencies

• Depends on #9068 (Multi-Account OAuth) for the Settings UI infrastructure

Acceptance Criteria

• [ ] OPENCODE_YOLO=true env var enables YOLO mode
• [ ] opencode --yolo CLI flag works
• [ ] Config option "yolo": true in opencode.json works
• [ ] Desktop Settings shows Danger Zone tab with toggle
• [ ] Toggle updates server state immediately
• [ ] All permission prompts are auto-approved in YOLO mode
• [ ] Clear warning messaging is displayed