Add quick test runner and enhance run_tests script

- Introduced `quick_test.py` for running specific test categories (unit, integration, theme, all).
- Updated `run_tests.py` to improve test execution and reporting, including coverage.
- Removed outdated test scripts for keyboard shortcuts, menu theming, note saving, and entry updating.
- Added new test script `test_theme_changing.py` to verify theme changing functionality.
- Consolidated integration tests into `test_integration.py` for comprehensive testing of TheChart application.
- Updated theme manager to ensure color retrieval works correctly.
- Modified test constants to import from the correct module path.

scripts/deprecated_test_update_entry.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+"""
+⚠️  DEPRECATED SCRIPT ⚠️
+
+This script has been consolidated into the new unified test suite.
+Please use the new testing structure instead:
+
+For theme testing:
+    .venv/bin/python scripts/quick_test.py theme
+
+For integration testing:
+    .venv/bin/python scripts/quick_test.py integration
+
+For all tests:
+    .venv/bin/python scripts/run_tests.py
+
+See TESTING_MIGRATION.md for full details.
+"""
+
+import sys
+
+print("⚠️  This script is deprecated. Please use the new test structure.")
+print("See TESTING_MIGRATION.md for migration instructions.")
+sys.exit(1)
+
+# Original script content below (preserved for reference):
+# """ + content[content.find('"""'):] if '"""' in content else content + """