Update dogfood template with support for tasks

[johnstcn]

A previous issue created a new template coder-dogfood-tasks which was basically a clone of our dogfood template with tasks support.

Update the existing dogfood template with the following:

• coder_app.develop_sh which is basically develop.sh running in a named screen session
• coder_app.preview which maps to port 8080 of develop.sh
• coder_parameter.ai_prompt required for task support
• module.claude-code for executing tasks
• desktop-commander MCP server installed and configured for Claude
• playwright MCP server installed and configured for Claude

All of the above should only be added when creating a task. Otherwise, the template should continue to function as-is.