test: add smoke import tests for app package

tests/test_app_import.py

@@ -0,0 +1,28 @@
+"""Smoke tests to catch import-time errors for the Shiny app package.
+
+These tests intentionally import `app.app` and `app.logger` to ensure the
+package is importable in different execution contexts (package vs script).
+"""
+from pathlib import Path
+import importlib
+import sys
+
+
+def _ensure_repo_on_path():
+    repo_root = Path(__file__).resolve().parents[1]
+    if str(repo_root) not in sys.path:
+        sys.path.insert(0, str(repo_root))
+
+
+def test_import_app_module():
+    """Import the app module and ensure `app` object exists."""
+    _ensure_repo_on_path()
+    mod = importlib.import_module("app.app")
+    assert hasattr(mod, "app"), "`app.app` must export `app`"
+
+
+def test_import_logger_module():
+    """Import the logging helper module to catch syntax/runtime import errors."""
+    _ensure_repo_on_path()
+    mod = importlib.import_module("app.logger")
+    assert hasattr(mod, "logger"), "`app.logger` must export `logger`"