Refactor setup and tool helpers for improved modularity and clarity

- Moved setup logic into dedicated files: agent.ts, config.ts, index.ts, workspace.ts.
- Introduced tool-helpers.ts for shared functions across tools, reducing boilerplate.
- Updated tools (status, task-comment, task-create, task-update, work-finish, work-start) to utilize new helper functions for workspace resolution and provider creation.
- Enhanced error handling and context detection in tools.
- Improved project resolution logic to streamline tool execution.
- Added new functionality for agent creation and configuration management in setup.

lib/notify.ts

@@ -33,7 +33,7 @@ export type NotifyEvent =
       issueTitle: string;
       issueUrl: string;
       role: "dev" | "qa";
-      model: string;
+      tier: string;
       sessionAction: "spawn" | "send";
     }
   | {
@@ -67,7 +67,7 @@ function buildMessage(event: NotifyEvent): string {
   switch (event.type) {
     case "workerStart": {
       const action = event.sessionAction === "spawn" ? "🚀 Started" : "▶️ Resumed";
-      return `${action} ${event.role.toUpperCase()} (${event.model}) on #${event.issueId}: ${event.issueTitle}\n🔗 ${event.issueUrl}`;
+      return `${action} ${event.role.toUpperCase()} (${event.tier}) on #${event.issueId}: ${event.issueTitle}\n🔗 ${event.issueUrl}`;
     }
 
     case "workerComplete": {