test: Add integration test to reproduce issue #397

Add test_remove_default_project_issue_397 that reproduces the bug
where a removed project still appears in 'bm project list'.

The test:
- Adds a new project and sets it as default
- Removes the original default project
- Verifies the removed project no longer appears in the list

This test will fail while the bug exists, confirming the issue.

Co-authored-by: Paul Hernandez <phernandez@users.noreply.github.com>

test-int/cli/test_project_commands_integration.py

@@ -119,3 +119,52 @@ def test_project_set_default(app_config, config_manager):
         for line in lines:
             if "another-project" in line:
                 assert "✓" in line
+
+
+def test_remove_default_project_issue_397(app_config, config_manager):
+    """Test that removed default project doesn't appear in list (issue #397).
+
+    Reproduces bug where 'main' project still shows in 'bm project list'
+    after being removed.
+    """
+    runner = CliRunner()
+
+    # Use a separate temporary directory to avoid nested path conflicts
+    with tempfile.TemporaryDirectory() as temp_dir:
+        new_project_path = Path(temp_dir) / "newmain"
+        new_project_path.mkdir()
+
+        # Step 1: Add a new project
+        result = runner.invoke(app, ["project", "add", "newmain", str(new_project_path)])
+        if result.exit_code != 0:
+            print(f"STDOUT: {result.stdout}")
+            print(f"STDERR: {result.stderr}")
+        assert result.exit_code == 0
+
+        # Step 2: Set the new project as default
+        result = runner.invoke(app, ["project", "default", "newmain"])
+        if result.exit_code != 0:
+            print(f"STDOUT: {result.stdout}")
+            print(f"STDERR: {result.stderr}")
+        assert result.exit_code == 0
+
+        # Step 3: Remove the original default project (test-project acts as "main")
+        result = runner.invoke(app, ["project", "remove", "test-project"])
+        if result.exit_code != 0:
+            print(f"STDOUT: {result.stdout}")
+            print(f"STDERR: {result.stderr}")
+        assert result.exit_code == 0
+
+        # Step 4: Verify test-project is NOT in the list
+        result = runner.invoke(app, ["project", "list"])
+        if result.exit_code != 0:
+            print(f"STDOUT: {result.stdout}")
+            print(f"STDERR: {result.stderr}")
+        assert result.exit_code == 0
+
+        # Bug: test-project still appears in list after removal
+        # Expected: test-project should NOT be in the output
+        assert "test-project" not in result.stdout, (
+            f"Bug reproduced: 'test-project' still appears in list after removal.\n"
+            f"Output:\n{result.stdout}"
+        )