[FEATURE]: grouped worktrees by workspaces

[mjlbach]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

I work in a non-monorepo (FE/BE services). I usually write in my AGENTS.md an explanation to keep a linked worktree for each BE/FE change. It would be nice to codify this in the UI, as right now I believe workspaces are limited to a single working directory, and furthermore the worktree are tracked according to each working directory.

To the best of my searching, this hasn't yet been suggested.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [FEATURE]: Multiple model usage with git worktrees #6679: Multiple model usage with git worktrees
• [FEATURE]: OpenCode Desktop WorkTrees / Columns / Horizontal or Vertical Panes #8372: OpenCode Desktop WorkTrees / Columns / Horizontal or Vertical Panes
• feat(session): add support for per-session working directories #9365: Allow sessions to have custom working directories (with linked PR)
• [FEATURE]: Ability to change keybinds in the CLI #9966: In desktop, with workspaces enabled, allow "New Workspace" to be initialized using an existing branch
• Desktop app: opening multiple git worktrees from the same repo replaces existing project #5638: Desktop app: opening multiple git worktrees from the same repo replaces existing project
• Support a root folder for aggregating sessions across subdirectories in Opencode #1877: Support a root folder for aggregating sessions across subdirectories in Opencode

Feel free to ignore if none of these address your specific case.