[FEATURE] Allow creating a new branch directly from the branch selector when no matches are found

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The branch selector in the bottom bar (next to the worktree toggle) only filters existing branches. When I type a name that doesn't exist yet, it shows "No hay ramas que coincidan" / "No matching branches" but gives no option to create the branch from there.

This forces me to either:

1. Ask Claude in the prompt to run git checkout -b <name>, or
2. Open a separate terminal, create the branch manually, and then reopen/refresh the selector.

Both break the flow when I'm starting a new task and just want to spin up a feature branch quickly.

Proposed Solution

When the typed name doesn't match any existing branch, show a "Create branch <name> from <current-branch>" option as the last item in the dropdown. Selecting it should run git checkout -b <name> (or create a worktree if worktree mode is active) and switch to it automatically.

Bonus: allow picking the base branch (default to current HEAD) inline.

Alternative Solutions

Current workarounds:

1. Asking Claude in the prompt to run git checkout -b <name>, which works but requires a full prompt cycle for what should be a one-click action.
2. Opening a separate terminal to run the git command manually, then refreshing the selector so the new branch shows up.

Both break the flow when starting a new task.

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

Example scenario:

1. I'm starting a new feature on my monorepo (Zuno ERP) and open Claude Code on the Code tab.
2. I click the branch selector in the bottom bar and type feat/custom-xxx.
3. The selector shows "No matching branches" — but gives me no way to create it.
4. With this feature, I could click "Create branch feat/custom-xxx from main" directly in the dropdown and start working immediately.
5. This would save me time because I create several feature branches per day and every one currently needs either a prompt round-trip or a context switch to a terminal.

Additional Context

_No response_