CRITICAL: Test artifact contamination violates repository architecture - 45 files in root directory

[krystophny]

Problem Statement

Test execution contaminated repository root with 45 artifact files, violating architectural standards and user experience.

Evidence

• Repository root contamination: 45 files (.png, .pdf, .txt, .log)
• Files detected: show_output.png, consolidated_mpeg_test_frame_0.png, test_basic_edge.png, cmake_formats.pdf, etc.
• Location violation: Artifacts belong in test/output/ directory structure
• Architectural impact: Polluted root directory breaks professional appearance

Expected Behavior

• All test artifacts MUST be placed in test/output/ subdirectories
• Repository root MUST remain clean (only essential config files)
• Tests MUST use proper output directory isolation

Technical Requirements

1. Immediate cleanup: Move existing artifacts to proper locations
2. Test architecture fix: Ensure all tests write to test/output/
3. CI enforcement: Block PRs that contaminate root directory
4. Architecture compliance: Maintain professional repository structure

Priority

CRITICAL - Repository architecture violation affecting user experience and project credibility

[krystophny]

Closing as duplicate of #990. Consolidating repository artifact contamination discussion and fixes under #990 to avoid split tracking.

[krystophny]

Duplicate of #990; tracking under #990.