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/atlas/index.ts

@@ -569,7 +569,7 @@ export function createSisyphusOrchestratorHook(
         }
 
         if (!isCallerOrchestrator(sessionID)) {
-          log(`[${HOOK_NAME}] Skipped: last agent is not orchestrator-sisyphus`, { sessionID })
+          log(`[${HOOK_NAME}] Skipped: last agent is not atlas`, { sessionID })
           return
         }