Feature: Add __main__.py for using with python -m

pyproject.toml

@@ -208,6 +208,9 @@ ignore = [
     "D107",   # Missing docstring in `__init__`
     "D401",   # First line should be in imperative mood
 ]
+unfixable = [
+    "T201",
+]
 
 [tool.ruff.lint.per-file-ignores]
 "docs/conf*.py" = ["ALL"]

src/subliminal/__main__.py

@@ -0,0 +1,26 @@
+"""Module subliminal."""
+
+from __future__ import annotations
+
+from textwrap import dedent
+
+if not (__name__ == '__main__' and __package__ == 'subliminal'):
+    import sys
+
+    print(  # noqa: T201
+        dedent(
+            f"""
+
+            The '__main__' module does not seem to have been run in the context
+            of a runnable package ... did you forget to add the '-m' flag?
+
+            Usage: {sys.executable} -m subliminal {' '.join(sys.argv[1:])}
+
+            """
+        )
+    )
+    sys.exit(2)
+
+from subliminal.cli import cli
+
+cli()