new workspace always branches from the current head

describe the bug

creating a new workspace (worktree) always branches from the current head of the project checkout.

the branch chip in the new session bar is display only. there is no way to pick the base branch before creating the workspace.

git worktree add --no-checkout -b <branch> <dir> is invoked with no start point, so whatever branch you happen to be sitting on becomes the base. if you are on a feature branch, the new workspace silently inherits it.

expected behavior

• the branch chip should be clickable
• clicking it should list local and remote branches with search
• in new workspace mode the selected branch becomes the base ref for git worktree add
• with no selection the workspace should branch from the repo default branch, not the current head
• in local or existing workspace mode selecting a branch should check it out

screenshots

(screenshots to be added)

environment

• desktop app, dev build, new layout
• macos