Workspace terminals are torn down when switching session routes

Description

Workspace terminals are torn down when navigating between chat routes.

The terminal cache is created per route inside TerminalProvider, which lives in the session page. Switching sessions (or moving between a draft and a session) destroys the previous terminal cache and disposes all terminal sessions, so an open bottom terminal disappears instead of persisting for the same workspace directory.

Plugins

n/a

OpenCode version

latest dev

Steps to reproduce

1. Open a workspace terminal in a chat.
2. Navigate to another chat in the same workspace directory (or open a new draft).
3. The bottom terminal is gone instead of persisting.

Screenshot and/or share link

n/a

Operating System

n/a (all)

Terminal

n/a