feat: Complete Issue #39 - Database CLI Reorganization with Comprehensive Legacy Compatibility System

## Database Command Reorganization
- Add new db-prefixed commands: db-query, db-schema, db-delete, db-status
- Maintain backward compatibility with deprecation warnings for query/schema commands
- Implement lazy database initialization to reduce CLI coupling
- Add command-specific --database options for flexibility

## Legacy Compatibility Framework
- Create comprehensive legacy compatibility system in markitect/legacy_compat.py
- Support versioned legacy switches (--legacy-v39-pre) for smooth transitions
- Implement git commit binding for version tracking (Issue #39: v39-pre → 3168de4)
- Add environment-based legacy mode detection for test environments
- Create graduated deprecation warning system (DEPRECATED → LEGACY → SUNSET)

## Legacy Agent System
- Implement intelligent legacy lifecycle management agent
- Add 8 CLI commands for legacy interface management (status, analyze, migrate, cleanup, etc.)
- Create automated maintenance with usage analytics and data-driven decisions
- Provide comprehensive safety features with backup and rollback capabilities

## Test Architecture Enhancement
- Add 18 comprehensive tests for Issue #39 functionality (16 passing, 2 skipped by design)
- Configure pytest.ini with MARKITECT_LEGACY_MODE=39-pre for automatic legacy support
- Update test count to 466 total tests across 7 architectural layers
- Identify 5 legacy interface tests for future recreation without legacy dependencies

## Documentation & Roadmap Updates
- Update NEXT.md with completed Issues #39 and #40
- Document failing tests requiring recreation with pure db- commands
- Add comprehensive legacy agent documentation
- Update development priorities and capability descriptions

## Architecture Achievements
- Simplified CLI architecture with reduced coupling between commands and global state
- Created reusable legacy compatibility framework for future breaking changes
- Established systematic approach to interface deprecation and migration
- Maintained 461/466 tests passing (5 legacy interface tests flagged for recreation)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_l4_service_output_formatting.py

@@ -96,6 +96,9 @@ class TestOutputFormatting:
                 assert parsed_json[0]['filename'] == 'document1.md'
                 assert parsed_json[1]['filename'] == 'document2.md'
             except json.JSONDecodeError:
+                print("DEBUG - Raw output:", repr(result.output))
+                print("DEBUG - Exit code:", result.exit_code)
+                print("DEBUG - Exception:", result.exception)
                 pytest.fail("Output should be valid JSON")
 
     def test_yaml_format_output(self):