Fetch checkpoint refs by URL to avoid polluting origin config

[Soph]

This does three things:

• adding a setting to enable fetch filtering for entire/checkpoints/v1 branches
• use the direct remote url instead of the remote name so a .git/config setting is only created for the url not the remote in general impacting all branches
• add an integration test guard that checks if operations touch .git/config and only allow expected changes.

Note:

Running 0.5.4 introduced fetches which will cause a change in the .git/config like:

[remote "origin"]
    promisor = true
    partialclonefilter = blob:none

This was an unintentional result of the changes when fetching

[Copilot]

Pull request overview

Updates the metadata/v2 fetch helpers to fetch checkpoint-related refs by explicit origin URL (instead of the origin remote name) to prevent git fetch --filter=... from persisting partial-clone settings into remote.origin.* in .git/config.

Changes:

• Add strategy.OriginURL() helper to resolve the configured origin fetch URL.
• Update multiple git fetch --filter=blob:none code paths to fetch by URL rather than remote name.
• Add a regression test asserting these fetch helpers do not set remote.origin.promisor / remote.origin.partialclonefilter.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
cmd/entire/cli/strategy/checkpoint_remote.go	Exposes OriginURL() to retrieve the origin remote URL for URL-based fetches.
cmd/entire/cli/git_operations.go	Switches several partial-clone fetch commands to use origin URL to avoid config pollution.
cmd/entire/cli/fetch_no_config_pollution_test.go	Adds regression coverage to ensure origin config is not modified by these fetches.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit d958ed4. Configure here.}