🤖 fix: creation view Send has no feedback when the branch list hangs or fails #6055

Problem

The creation view now keeps Send disabled until the branch list loads, for every runtime except local (#6035, fix for #6033). Two edge cases of the branch load are still rough.

1. A listBranches call that never settles keeps Send disabled with no explanation. The backend listBranches (src/node/services/projectService.ts, around line 1730) has no timeout. Before 🤖 fix: a new workspace waits for its branch list before it can be sent #6035, the user got the "Trunk branch is required" toast instead.
2. A rejected listBranches gives the old backend toast. useCreationWorkspace.ts sets branchesLoaded to true in finally, so the trunk stays empty and a worktree send shows "Trunk branch is required for worktree and SSH runtimes". This behavior existed before 🤖 fix: a new workspace waits for its branch list before it can be sent #6035, and it is not a regression.
3. Minor, old code: the loadBranches callback used after git init (useCreationWorkspace.ts, around lines 334-346) has no mounted guard. A project switch during git init can apply stale branches.

Possible fix (not designed yet)

• Put a timeout on listBranches, or show a short "loading branches" state next to the disabled Send.
• When the branch load fails, show a clear inline message (for example "Could not load branches") instead of the backend toast.
• Add the mounted guard to the git-init callback.

Found by the clean-context readiness review of #6035. Not reproduced by hand. Related: #6033, #6038.

Owner: coordinator desk.

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