fix(git-guards): replace 'branch' with 'worktree' in error messages

[JacobPEvans]

Summary

Replace "main branch" with "main worktree" in error messages to clarify terminology and prevent Claude from misinterpreting the guard's intent. Users were creating git branches instead of worktrees when blocked by the guard, indicating confusion about whether "main branch" meant the branch name or the literal main worktree directory.

Changes

• main-branch-guard.sh: Updated error message from "Editing files on the main branch is not allowed" to "Editing files in the main worktree is not allowed"
• main-branch-guard.sh: Changed second message from "Current branch is 'main'" to "You are in the main worktree" (more accurate and clearer)
• main-branch-guard.py: Applied same messaging updates to Python implementation for consistency

All changes are user-facing error messages only — no logic changes.

Test Plan

• Trigger main-branch-guard by attempting to edit a file in the main/ worktree
• Verify error message says "main worktree" instead of "main branch"
• Verify Claude responds by creating a worktree (not a git branch) when blocked
• Confirm both shell and Python guards have consistent messaging

[Copilot]

Pull request overview

This PR updates the user-facing deny reasons emitted by the main-branch-guard hooks to prefer “main worktree” terminology, aiming to steer users/Claude toward creating Git worktrees instead of creating branches when edits are blocked.

Changes:

• Updated deny message when the file is detected under a main/ worktree directory to say “main worktree”.
• Updated deny message for the fallback “on main” detection path to also say “main worktree” (in both shell and Python implementations).

Reviewed changes

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

File	Description
git-guards/scripts/main-branch-guard.sh	Adjusts permissionDecisionReason strings to say “main worktree”
git-guards/scripts/main-branch-guard.py	Adjusts permissionDecisionReason strings to say “main worktree”

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[gemini-code-assist]

Code Review

This pull request updates the error messages in both the Python and Shell versions of the main branch guard script to use 'main worktree' terminology instead of 'main branch'. The review feedback suggests including the specific file path in all error messages for better context and consistency across the scripts. Additionally, it was noted that these hooks should exit with code 0 when returning a JSON payload, even for 'deny' decisions.