refactor(plugin): update atlas references

Update plugin handlers, commands, and integration points to use 'atlas' agent name. Start-work command and config handler now reference 'atlas'.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/start-work/index.ts

@@ -71,7 +71,7 @@ export function createStartWorkHook(ctx: PluginInput) {
         sessionID: input.sessionID,
       })
 
-      updateSessionAgent(input.sessionID, "orchestrator-sisyphus")
+      updateSessionAgent(input.sessionID, "atlas")
 
       const existingState = readBoulderState(ctx.directory)
       const sessionId = input.sessionID