feat: add OmO config with build agent hiding and startup toast

- Add configurable build agent hiding (omo_agent.disable_build)
- Add startup-toast hook to show version on OpenCode startup
- Fix auto-update-checker to respect version pinning

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/config/index.ts

@@ -5,6 +5,7 @@ export {
   McpNameSchema,
   AgentNameSchema,
   HookNameSchema,
+  OmoAgentConfigSchema,
 } from "./schema"
 
 export type {
@@ -14,4 +15,5 @@ export type {
   McpName,
   AgentName,
   HookName,
+  OmoAgentConfig,
 } from "./schema"