[minion] partio enable restores metadata branch from remote on fresh clones

[jcleira]

Objective

When partio enable is run in a freshly cloned repo where no local partio/checkpoints/v1 branch exists but a remote one does, automatically create the local branch tracking the remote. This preserves checkpoint history for developers who clone an existing repo and enables without needing a manual git fetch step.

Acceptance Criteria

• On a fresh clone, partio enable checks for a remote partio/checkpoints/v1 branch
• If found, the local branch is created tracking the remote before hooks are installed
• If no remote branch exists, behavior is unchanged (new branch created on first commit)
• A message is printed informing the user that existing checkpoint history was restored
• Documented in the enable command help and onboarding docs

Source

Resolves entireio/cli#511 (changelog 0.4.8)

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Automated PR by partio-io/minions · Task: enable-restore-metadata-branch-on-clone

Created by an unattended coding agent. Please review carefully.

[jcleira]

Related PR: partio-io/docs#12