fix: isolate test artifacts from production asset registry

- Create tests/test_utils.py with utilities for consistent test workspace management
- Fix tests to use project tmp/ directory instead of system /tmp
- Ensure all AssetManager instances in tests use isolated registries
- Prevent contamination of production asset_registry.json during testing

Key changes:
- test_issue_142_asset_manager.py: Fix AssetManager() calls to use test workspaces
- test_issue_144_batch_import.py: Use create_test_workspace() and get_test_asset_config()
- test_issue_145_production_error_handler.py: Use test_workspace() context manager
- tests/test_utils.py: New utilities for isolated test environments

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

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

tests/test_issue_144_batch_import.py

@@ -8,14 +8,13 @@ Issue #144: Phase 3 - Advanced Features and Performance
 """
 
 import pytest
-import tempfile
-import shutil
 from pathlib import Path
 from unittest.mock import Mock, patch, MagicMock
 import json
 
 from markitect.assets import AssetManager, AssetError
 from markitect.assets.batch_processor import BatchAssetProcessor, BatchImportResult, ConflictResolution, ProgressReporter
+from tests.test_utils import create_test_workspace, get_test_asset_config
 
 
 class TestBatchAssetImport:
@@ -23,9 +22,9 @@ class TestBatchAssetImport:
 
     def setup_method(self):
         """Set up test environment with temporary directories and mock assets."""
-        self.temp_dir = tempfile.mkdtemp()
-        self.source_dir = Path(self.temp_dir) / "source"
-        self.assets_dir = Path(self.temp_dir) / "assets"
+        self.temp_dir = create_test_workspace("batch_import")
+        self.source_dir = self.temp_dir / "source"
+        self.assets_dir = self.temp_dir / "assets"
 
         self.source_dir.mkdir()
         self.assets_dir.mkdir()
@@ -47,16 +46,14 @@ class TestBatchAssetImport:
         nested_dir.mkdir(parents=True)
         (nested_dir / "nested_image.png").write_bytes(b"nested content")
 
-        self.asset_manager = AssetManager(config={
-            'assets': {
-                'storage_path': str(self.assets_dir),
-                'registry_path': str(self.assets_dir / 'registry.json')
-            }
-        })
+        # Use test asset configuration to ensure isolated registry
+        config = get_test_asset_config(self.temp_dir)
+        self.asset_manager = AssetManager(config)
 
     def teardown_method(self):
         """Clean up temporary directories."""
-        shutil.rmtree(self.temp_dir)
+        import shutil
+        shutil.rmtree(self.temp_dir, ignore_errors=True)
 
     def test_batch_processor_initialization(self):
         """Test BatchAssetProcessor can be initialized with AssetManager."""