feat: add automatic pre-commit hook setup for dev containers

[sohal]

Implement zero-configuration pre-commit integration for downstream users with automatic hook installation on container startup.

Changes:

• Add setup-pre-commit script for automatic hook configuration
• Update Dockerfile to install setup script in user PATH
• Configure devcontainer.json with setup-pre-commit in postCreateCommand
• Add comprehensive test suite for pre-commit auto-setup functionality
• Create example templates for downstream projects (devcontainer + config)
• Update documentation (README, DEVCONTAINER.md, PRE-COMMIT.md)
• Add CI/CD tests for hook installation and execution

Key Features:

• Pre-commit binary pre-installed in Docker image
• Auto-detects git repos and .pre-commit-config.yaml files
• Installs hooks automatically on dev container creation
• Idempotent setup (safe to run multiple times)
• Graceful handling of non-git directories
• Zero manual configuration required for downstream users

Downstream Usage:
Users only need to add .pre-commit-config.yaml to their project root and include setup-pre-commit in their devcontainer postCreateCommand. Hooks install automatically when the container starts.

Testing:

• Local test script: ./scripts/test.sh precommit
• CI/CD tests cover all scenarios (no git, no config, with config)
• Verifies hook installation, idempotency, and execution

Closes #14

Description

Please include a summary of the changes and the related issue.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Testing

• I have tested the Docker image builds successfully
• I have tested the tools work correctly inside the container
• I have verified ARM toolchains function properly
• I have updated the documentation accordingly

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published