Move PushChanges to separate interface to improve testing

[geofflamrock]

Moves StackHelpers.PushChanges into StackActions to improve the ability to test commands without needing to have a full Git repo.

Part of a series of PRs:

• Cleanup unused methods in GitClient #323
• Move PullChanges to separate interface to improve testing #326
  • Move PushChanges to separate interface to improve testing #327
    • Move UpdateStack to separate interface to improve testing #328
      • Cache GitHub pull requests to improve performance #329
• Refactor delete stack tests to not need a full Git repo #330
• Refactor new stack tests to not use full Git repo #332
• Refactor stack switch tests to not use full Git repo #333
• Refactor add branch tests to not use full Git repo #341
• Refactor new branch tests to not use full Git repo #342
• Refactor stack status tests to not use a full Git repo #346
• Change more push stack tests to not use a full Git repo #347
• Change create pull requests tests to not use full Git repo #349

[Copilot]

Pull Request Overview

This PR refactors the push functionality by moving StackHelpers.PushChanges to a separate IStackActions interface to improve testability. This allows commands to be tested without requiring a full Git repository setup, using mock interfaces instead.

Key changes:

• Extracted PushChanges method from static helper to injectable service
• Updated command handlers to use new IStackActions dependency
• Refactored tests to use mocks instead of real Git repositories

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
SyncStackCommand.cs	Updated to call stackActions.PushChanges() instead of static helper
PushStackCommand.cs	Added IStackActions dependency and updated constructor/method calls
StackHelpers.cs	Removed static PushChanges method
StackActions.cs	Added PushChanges method to interface and implementation
PushStackCommandHandlerTests.cs	Refactored tests to use mocks instead of real Git repositories
StackHelpersTests.cs	Removed test for moved PushChanges method
StackActionsTests.cs	Added comprehensive tests for new PushChanges functionality

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