Allow specifying working directory when dispatching sessions from Agent View TUI

Summary

When using Agent View (claude agents) to manage multiple Claude Code instances, there's no way to dispatch a new session into a different working directory from within the TUI. You have to exit, cd to the target directory in a separate terminal, run claude --bg, and switch back.

Motivation

When working across multiple projects or subdirectories in a monorepo, the current workflow requires leaving the Agent View to dispatch a session in a different directory. This breaks the flow of the centralized agent management experience.

Proposed solution

Allow specifying the target working directory when creating a new session from within the Agent View TUI — for example, via a directory picker or a text input when dispatching a new agent.

Related issues

• #49429 — Session-scoped working directory / git branch state
• #61366 — Allow /branch and --resume to target a different working directory
• #50302 — Allow switching project context mid-session