feat(cursor-origin): Read a commit with its changed files

[wedamija]

Add support for reading a single commit with its stats and changed files, and for listing a commit's changed files. Origin returns files separately, so the commit response includes only the first 100 files.

[sentry]

Bug: The code uses unsafe direct dictionary access (raw["stats"], raw["patch"]) on an API response, which will raise a KeyError if the keys are missing.
_{Severity: HIGH}

Suggested Fix

Use the .get() method with a default value to safely access potentially missing keys from the API response. For example, access stats with stats = raw.get("stats") or {} and then additions=stats.get("additions"). Similarly, access the patch with patch=raw.get("patch").

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: src/scm/providers/cursor_origin/provider.py#L496-L497

Potential issue: The `get_commit` method and its helper `map_commit_file` in the Cursor
Origin provider use direct dictionary access to parse the API response. Specifically,
`raw["stats"]["additions"]`, `raw["stats"]["deletions"]`, and `raw["patch"]` are
accessed without checking if the keys exist. If the API returns a commit object without
a `stats` field (e.g., for an empty commit) or a file object without a `patch` field,
the application will raise a `KeyError` and crash while processing the commit. This
contrasts with the more defensive `.get()` approach used in other SCM providers like
GitHub.

Also affects:

• src/scm/providers/cursor_origin/provider.py:523~523

_{Did we get this right? 👍 / 👎 to inform future reviews.}