feat: Add test scripts and runner for TheChart application

- Created demo_failing_test.py to demonstrate pre-commit blocking with a failing test.
- Added run_tests.py for executing all tests with coverage reporting.
- Introduced test.py as a quick test runner for the application, providing coverage reports and user-friendly output.

scripts/demo_failing_test.py

@@ -0,0 +1,19 @@
+"""
+Demonstration script to show pre-commit test blocking.
+This creates a temporary failing test to demonstrate the pre-commit behavior.
+"""
+
+# Create a simple test file that will fail
+test_content = '''
+def test_that_will_fail():
+    """This test is designed to fail to demonstrate pre-commit blocking."""
+    assert False, "This test intentionally fails"
+'''
+
+with open("tests/test_demo_fail.py", "w") as f:
+    f.write(test_content)
+
+print("Created temporary failing test: tests/test_demo_fail.py")
+print("Now try: git add . && git commit -m 'test commit'")
+print("The commit should be blocked by the failing test.")
+print("Remove the file with: rm tests/test_demo_fail.py")