fix(cli): scope headless git credentials

[BunsDev]

Motivation

• The headless runtime previously installed an unscoped Git credential helper that returned COVEN_GIT_TOKEN for any get request, allowing token exfiltration to attacker-controlled HTTPS remotes.
• The change confines credential responses to the existing origin GitHub https://github.com/<owner>/<repo> remote and enables path-aware lookups to prevent accidental disclosure.

Description

• Add origin parsing and quoting helpers (origin_github_repo_path, github_repo_path_from_url, shell_single_quote) and require an origin GitHub path before installing a helper.
• Replace the unconditional helper with a shell snippet that parses Git's stdin (protocol, host, path) and only emits credentials when protocol=https, host=github.com, and path matches the repo owner/repo (accepting an optional .git suffix).
• Enable credential.useHttpPath = true so Git passes repository paths to the helper, allowing the helper to reject non-origin requests.
• Add regression tests that assert the helper references $COVEN_GIT_TOKEN (not the literal token), that the helper is scoped to the origin path, that useHttpPath is set, and that the helper does not return the token for attacker-controlled credential requests.

Testing

• Ran cargo fmt --all successfully.
• Ran cargo test --package claurst --no-default-features configure_git_auth -- --nocapture, and the headless configure_git_auth unit tests passed.
• Ran cargo check --workspace --no-default-features, which succeeded.
• cargo check --workspace failed in this environment due to a missing system dependency (alsa.pc) unrelated to this change.
• cargo clippy --workspace --all-targets --no-default-features -- -D warnings failed due to pre-existing clippy::collapsible_if warnings in crates/tui/src/image_paste.rs, which are outside the scope of this fix.

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Codex Task

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview	Jul 27, 2026 12:12pm

[Copilot]

Pull request overview

This PR hardens the headless CLI’s Git authentication by scoping the installed credential helper so it only returns COVEN_GIT_TOKEN for the repository’s existing origin https://github.com/<owner>/<repo> remote (and enabling path-aware lookups to prevent token disclosure to other HTTPS remotes).

Changes:

• Parse and require a GitHub origin repo path before installing the credential helper.
• Replace the unconditional helper with a stdin-parsing helper that checks protocol=https, host=github.com, and matching path (with optional .git).
• Add regression tests asserting the helper remains env-backed, is scoped to origin, enables credential.useHttpPath, and rejects attacker-controlled credential requests.

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