Bug

When creating a session targeting a git repository that has been initialized (git init) but has no commits yet, the session creation fails with:

Checking out master...
Branch "master" does not exist. Pass createBranch to create it.

Root Cause

In server/git-utils.ts, checkoutOrCreateBranch() runs git checkout <branch> which fails on empty repos because the branch doesn't technically exist yet (it's an "unborn" branch — HEAD points to refs/heads/master symbolically, but no commit backs it).

Additionally, getRepoInfo() uses git rev-parse --abbrev-ref HEAD which fails on unborn branches and falls back to "HEAD", causing the currentBranch !== body.branch check to always be true — so it always attempts the checkout even though we're already on the intended branch.

Steps to Reproduce

1. Create an empty git repo: mkdir test && cd test && git init
2. Open Companion and create a session pointing to this directory
3. Session creation fails at the "Checking out master..." step

Proposed Fix

1. getRepoInfo(): Fall back to git symbolic-ref --short HEAD when rev-parse --abbrev-ref HEAD fails — this correctly returns the unborn branch name (e.g. master or main)
2. checkoutOrCreateBranch(): Detect empty repos (no commits) early. If the requested branch matches the current unborn branch, return successfully. If a different branch is requested, use git checkout --orphan <branch> instead of regular checkout.

Environment

• Companion v0.72.0
• Repo: git init with files but zero commits
• Branch: master (default from git init)