Auto-resolve non-conflicting changes in merge conflicts

[giovannipapini-agilelab]

Summary

When resolving merge conflicts, provide an "auto-resolve" / "magic merge" button that automatically accepts all non-conflicting changes from both sides, leaving only true conflicts for manual resolution.

Description

IntelliJ IDEA has a "Magic Merge" button in its merge tool that automatically resolves all non-conflicting hunks in a 3-way merge. This is extremely useful when most of a file's changes don't actually conflict — you click one button, and only the real conflicts remain.

Currently, Zed's conflict resolution requires manually accepting each hunk (ours/theirs) even when many of them are unambiguous. An auto-resolve feature would:

1. Identify hunks that only changed on one side (local or remote, but not both)
2. Automatically accept those changes
3. Leave only genuinely conflicting hunks for the user to resolve manually

This is a standard feature in tools like IntelliJ IDEA ("Magic Merge"), kdiff3 ("Auto-Merge"), and VS Code ("Accept All Non-Conflicting").

Use case

Large merges or rebases where most changes don't conflict — manually resolving dozens of unambiguous hunks is tedious and error-prone when a tool could do it instantly.