[BUG] rtk git branch -a omits remote branches; -r works correctly

Description

rtk git branch -a only outputs the current local branch, silently dropping all remotes/origin/* lines. The -r flag works correctly and shows remote branches.

Steps to reproduce

# Repo with a pushed remote (origin/main)
rtk git branch -a
# Output:
# * main

rtk git branch -r
# Output:
# *
#   origin/HEAD -> origin/main
#   origin/main

# Native git (bypassing rtk) works correctly:
/usr/bin/git branch -a
# * main
#   remotes/origin/HEAD -> origin/main
#   remotes/origin/main

Expected behavior

rtk git branch -a should display both local and remote-tracking branches, matching native git branch -a output.

Environment

• rtk version: 2.3.3
• OS: macOS Darwin 25.5.0
• Shell: zsh

Notes

• rtk help for git branch describes it as "Compact branch listing (current/local/remote)", suggesting remote display is intended.
• Workaround: use /usr/bin/git branch -a to bypass the hook.
• Related: #1499 (branch -vv strips tracking markers)

Start with the rtk git branch command path and compare its handling of -a with the working -r path and native /usr/bin/git branch -a. Reproduce the issue in a repository with origin/main; done means rtk git branch -a includes local and remote-tracking branches like native Git.