Continue repo.sh ownership reduction for GitHub settings and Project delegation

[codeforester]

Goal

Continue the documented basectl repo ownership reduction by separating GitHub repository settings, branch-protection payloads, and Project metadata delegation from local baseline generation where that can be done without changing behavior.

Background

docs/repo-command-ownership.md records that repo.sh has already had repo installer-template and repo agent-guidance extracted into command-owned helpers. The same map names GitHub repository settings, branch-protection payloads, and Project metadata delegation as follow-up candidates. Current repo.sh still combines local baseline writers, GitHub repo creation/configuration, default branch ruleset payloads, Project metadata handoff, PR branch/worktree helpers, clone, checks, and dispatch. The reason to split is ownership clarity around these responsibilities, not raw line count.

Scope

• Re-read docs/repo-command-ownership.md and confirm the current implementation still matches its responsibility map.
• Extract one cohesive GitHub settings boundary if it is still natural, such as repository labels/settings plus default-branch ruleset payload helpers.
• Keep shared path, dry-run, Git, and PR worktree primitives in repo.sh unless multiple extracted commands prove a smaller common helper is needed.
• Keep structured GitHub Project semantics in Python or existing Project engines rather than adding more shell policy.
• Update the ownership doc to record what moved and what intentionally stayed.

Acceptance Criteria

• Public basectl repo init, repo configure, repo clone, repo check, repo agent-guidance, and repo installer-template behavior is unchanged.
• The extracted boundary has a command-specific or responsibility-specific name and tests that match the moved behavior.
• Existing generated PR and Project metadata flows continue to work.
• docs/repo-command-ownership.md is current after the change.
• The PR explains why the split is a natural ownership reduction, not a cosmetic file-size edit.

Validation

• Focused BATS coverage for repo configure, repo init, generated PR flows, and any moved helper behavior.
• Relevant GitHub helper tests if Project or ruleset handoff is touched.
• git diff --check.

Non-Goals

• Do not rewrite basectl repo in Python in this slice.
• Do not move generic GitHub shell helpers to base-bash-libs in this issue.
• Do not split every section of repo.sh.
• Do not change generated repository baseline files or GitHub Project field semantics.

Project Fields

• Priority: P3
• Status: Backlog
• Size: M
• Area: Shell
• Initiative: Contract Hardening

Agent Assignment

Human first. This is refactor work with public behavior preservation and should be reviewed against the ownership map before implementation.