chore: overhaul CLI messaging and terminal output formatting

[Huerte]

Type

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

Overview

this fixes the mixed tone in the cli messages and cleans up the terminal spacing. no more weird blank lines or robotic sounding prompts.

Changes

• colors.py: added a banner helper that scales to terminal width and fixed the double spacing issue globally
• pull.py, undo.py: fixed bugs where error strings were squashed together without spaces
• jump.py, state.py: ripped out filler words like "please check" and made prompts direct
• main.py, git_operations.py: applied short military style banners for major operations
• executor.py: cleaned up error outputs so you actually see what command to run next

How to Test

1. pip install -e ".[dev]"
2. pytest -v
3. Expected result: all 150 tests pass. you can also run gitgo push on a test repo to see the new banners.

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)