Fix compose scan failures

[Kurrisua]

Pull Request

Description

Surface Docker Compose service scan failures in the CLI Quick take summary.

When a Compose service image or Dockerfile scan fails, DockSec previously only recorded that failure through internal logging. This could make a Compose scan look complete even when one or more services were not actually scanned.

This PR tracks failed service scans with the service name, scan type, and a short reason, returns that metadata from ComposeOrchestrator.run_full_scan(), and renders it in the user-facing Quick take block.

Closes #131

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Code style update (formatting, renaming)
• Code refactoring (no functional changes)
• Performance improvement
• Test update
• Build / CI configuration
• Security fix

How Has This Been Tested?

Describe the tests run to verify the changes:

• Unit tests
• Manual testing

Test Configuration:

• Python version: Python 3.14
• Operating System: macOS
• DockSec version: source checkout from main

Commands run:

.venv/bin/python -m pytest tests/test_compose_scanner.py tests/test_output.py -q
.venv/bin/python -m py_compile docksec/compose_scanner.py docksec/cli.py tests/test_compose_scanner.py