Add repository baseline: layout, tooling, assets, README, Doxyfile and CI (MIL-001)

Task: MIL-001#1
Task: MIL-001#2
Task: MIL-001#3
Task: MIL-001#4
Task: MIL-001#5
Task: MIL-001#6

tests/test_constants.py

@@ -0,0 +1,17 @@
+"""Smoke test: the constants point at the assignment files that ship with the game."""
+
+from us_states_game import constants
+
+
+def test_data_files_exist() -> None:
+    assert constants.STATES_CSV_PATH.is_file()
+    assert constants.MAP_IMAGE_PATH.is_file()
+
+
+def test_states_csv_has_all_states() -> None:
+    lines = constants.STATES_CSV_PATH.read_text(encoding="utf-8").strip().splitlines()
+    assert (
+        lines[0]
+        == f"{constants.STATE_COLUMN},{constants.X_COLUMN},{constants.Y_COLUMN}"
+    )
+    assert len(lines) - 1 == constants.NUMBER_OF_STATES