fix(gitRoutes): block edits on default branch

[donhardman]

• Prevent commits, discards, undo, and redo on default branch
• Return 403 error to enforce branching workflow

[Copilot]

Pull Request Overview

This PR implements protection for the default branch by preventing direct modifications. It adds a new isOnDefaultBranch helper function and enforces a branching workflow by blocking commits, file operations (save, move, delete), directory creation, and git operations (discard, undo, redo) when users are on the default branch (main/master).

Key Changes:

• Added isOnDefaultBranch helper function to check current branch status
• Implemented 403 error responses across multiple routes when operations are attempted on default branch
• Enhanced error messages to guide users toward creating new branches

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
ui/helpers.js	Adds new isOnDefaultBranch function that checks if the current branch matches the default branch
ui/routes.js	Adds default branch checks to file operations (save, move, delete) and directory creation endpoints
ui/gitRoutes.js	Adds default branch checks to git operations (commit, discard, undo, redo) endpoints

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The git.revparse() call returns a string with a trailing newline character. This needs to be trimmed before comparison with defaultBranch to avoid false negatives when checking currentBranch === defaultBranch.

Suggested change

	const currentBranch = await git.revparse(['--abbrev-ref', 'HEAD']);
	const currentBranch = (await git.revparse(['--abbrev-ref', 'HEAD'])).trim();

[Copilot]

This branch check logic is duplicated across multiple endpoints (lines 495-506, 623-634, 669-680, 736-747 in routes.js and lines 628-637, 808-817, 1119-1128, 1261-1270 in gitRoutes.js). Consider extracting this into a reusable middleware function to reduce code duplication and improve maintainability.