feat(agents): add OmO orchestrator agent

- Add OmO agent: powerful AI orchestrator for complex task delegation
- Implements parallel background agent execution and todo-driven workflows
- Emphasizes aggressive subagent delegation with 7-section prompt structure

Co-authored-by: huynguyen03dev <huynguyen03dev@users.noreply.github.com>
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src/agents/types.ts

@@ -1,6 +1,7 @@
 import type { AgentConfig } from "@opencode-ai/sdk"
 
 export type BuiltinAgentName =
+  | "OmO"
   | "oracle"
   | "librarian"
   | "explore"