Add 'Diff With Commit' action

[davidbonan]

Summary

Add a new command "git: Diff With Commit" that allows users to compare the current version of a file with any previous commit that modified it.

Features

• Opens a commit picker modal showing the last 50 commits that modified the current file
• Each commit displays: short SHA, author name, commit subject, and relative timestamp
• Supports fuzzy search across SHA, author, subject, and message
• Opens a diff view in a new tab showing changes between the selected commit and the current version

Implementation

• Added DiffWithCommit action to git actions
• Added show_file method to GitRepository trait to retrieve file content at a specific commit via git show :
• Created CommitDiffPicker modal for commit selection
• Created CommitFileDiffView for displaying the diff using the existing BufferDiff infrastructure

gitdiff.mov

Release Notes:

• Added "git: Diff With Commit" command to compare the current file against any previous commit that modified it.

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[davidbonan]

@cla-bot check

[cla-bot]

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[cole-miller]

Hi, thanks for opening a PR! I think this will be easier to review and hopefully get merged if you can break it up into smaller pieces. In particular, the commit picker seems like a useful feature in its own right (to start out with, selecting an entry could just show the diff from that commit for the entire project, using the existing CommitView infrastructure). Would you mind resubmitting that as its own PR?

[cole-miller]

Closing due to lack of response, but I like the idea of the commit picker, please feel free to reopen with that as the focus!