Issue Title
[Docs] Incorrect Oh-My-OpenCode configuration: "frontend-ui-ux-engineer" is not an agent
Description
The README section "Using with Oh-My-OpenCode" suggests configuring frontend-ui-ux-engineer and document-writer under the agents key.
Problem
In the latest Oh-My-OpenCode architecture, these are NOT static agents but dynamic roles generated from Categories. Configuring them under agents has no effect, leading to model fallback (usually to default Anthropic/OpenAI models instead of the user's intended Gemini models).
Solution
The documentation should instruct users to configure the categories key instead:
frontend-ui-ux-engineer → categories.visual-engineering
document-writer → categories.writing
This ensures that delegate_task calls correctly utilize the configured Antigravity models.