chore: remove allow_fail flag and use exception-based architecture

[Huerte]

Type

• Bug fix
• New feature
• Documentation
• Refactor / internal

Overview

Removed the allow_fail flag from run_command in favor of a try/except architecture. This fixes the issue of silent bugs happening when we forget to manually check if a command failed. It forces the code to handle the GitCommandError explicitly.

Closes #74

Changes

• utils/executor.py: Removed allow_fail from run_command. It now always throws a GitCommandError on failure.
• Command modules: Replaced manual error checks with standard try/except GitCommandError blocks across the app.
• CHANGELOG.md: Added notes about the new exception-based architecture.

How to Test

1. pip install -e ".[dev]"
2. pytest
3. Expected result: All 198 tests should pass with no errors.

Checklist

• I tested my changes locally and they work
• I updated CHANGELOG.md under the [Unreleased] section
• I updated README.md (if I added or changed a command)
• I added or updated tests for my change (if applicable)
• My change does not break any existing commands (if it does, describe the impact in the Overview)