Add tests and publish repository metadata for MIL-003

Add 19 pytest tests covering the report, resource check, coin
processing, refunds, change, profit, make_coffee and the main loop.
Add a tests package and put the project root on the pytest path.
Doxygen output is clean. The repository description and topics were set
on the git host.

Closes #13
Closes #14
Closes #15
Closes #16
Closes #17

Task: MIL-003#1
Task: MIL-003#2
Task: MIL-003#3
Task: MIL-003#4
Task: MIL-003#5

tests/test_resources.py

@@ -0,0 +1,52 @@
+"""!
+@file test_resources.py
+@brief Tests for the report and the resource check.
+"""
+
+import pytest
+
+from coffee_machine.constants import INITIAL_RESOURCES, MENU
+from coffee_machine.main import format_money, is_resource_sufficient, report
+
+
+def test_format_money_shows_two_decimals() -> None:
+    """!
+    @brief Cents are shown as dollars with two decimals.
+    """
+    assert format_money(250) == "$2.50"
+    assert format_money(0) == "$0.00"
+
+
+def test_report_prints_resources_and_money(capsys: pytest.CaptureFixture[str]) -> None:
+    """!
+    @brief The report lists each resource with its unit, then the money.
+    """
+    report({"water": 300, "milk": 200, "coffee": 100}, 250)
+    assert capsys.readouterr().out == (
+        "Water: 300ml\nMilk: 200ml\nCoffee: 100g\nMoney: $2.50\n"
+    )
+
+
+def test_is_resource_sufficient_when_enough() -> None:
+    """!
+    @brief An order is accepted when every ingredient is available.
+    """
+    assert is_resource_sufficient(MENU["latte"]["ingredients"], INITIAL_RESOURCES)
+
+
+def test_is_resource_sufficient_when_exactly_enough() -> None:
+    """!
+    @brief Using up an ingredient completely is allowed.
+    """
+    assert is_resource_sufficient({"water": 300}, {"water": 300})
+
+
+def test_is_resource_sufficient_names_missing_resource(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """!
+    @brief A short ingredient is refused and named.
+    """
+    resources = {"water": 300, "milk": 100, "coffee": 100}
+    assert not is_resource_sufficient(MENU["latte"]["ingredients"], resources)
+    assert capsys.readouterr().out == "Sorry there is not enough milk.\n"