feat: add Akkudoktor feed-in provider (#1187)

The `FeedInTariffAkkudoktor` provider uses raw day-ahead market prices from
`https://api.akkudoktor.net/prices` as `feed_in_tariff_wh`. It does not add electricity import
charges or VAT. Published prices are extended to the configured prediction horizon with the same
seasonal ETS or median fallback used by the Akkudoktor electricity-price provider.

The Akkudoktor endpoint currently forwards hourly market prices from aWATTar. With a 15-minute
optimization interval, EOS holds each hourly price constant for its four quarter-hour slots. This
keeps the slot grid consistent but does not create genuine quarter-hour market prices.

Signed-off-by: Andreas Schmitz <akkudoktor.net>
Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

tests/test_feedintariffakkudoktor.py

@@ -0,0 +1,100 @@
+import asyncio
+import json
+from unittest.mock import Mock, patch
+
+import pytest
+import pytest_asyncio
+
+from akkudoktoreos.core.coreabc import get_ems
+from akkudoktoreos.prediction.elecpriceakkudoktor import AkkudoktorElecPrice
+from akkudoktoreos.prediction.feedintariffakkudoktor import FeedInTariffAkkudoktor
+from akkudoktoreos.utils.datetimeutil import to_datetime, to_duration
+
+
+@pytest.fixture
+def provider(config_eos):
+    config_eos.merge_settings_from_dict(
+        {
+            "elecprice": {"charges_kwh": 0.30},
+            "feedintariff": {"provider": "FeedInTariffAkkudoktor"},
+        }
+    )
+    value = FeedInTariffAkkudoktor()
+    value.highest_orig_datetime = None
+    value.records.clear()
+    assert value.enabled()
+    return value
+
+
+@pytest.fixture
+def response_data():
+    return {
+        "meta": {
+            "start_timestamp": "1733871600",
+            "end_timestamp": "1733958000",
+            "start": "2024-12-11T00:00:00+01:00",
+            "end": "2024-12-12T00:00:00+01:00",
+        },
+        "values": [
+            {
+                "start_timestamp": 1733871600,
+                "end_timestamp": 1733875200,
+                "start": "2024-12-11T00:00:00+01:00",
+                "end": "2024-12-11T01:00:00+01:00",
+                "marketprice": 100.0,
+                "unit": "Eur/MWh",
+                "marketpriceEurocentPerKWh": 10.0,
+            },
+            {
+                "start_timestamp": 1733875200,
+                "end_timestamp": 1733878800,
+                "start": "2024-12-11T01:00:00+01:00",
+                "end": "2024-12-11T02:00:00+01:00",
+                "marketprice": 200.0,
+                "unit": "Eur/MWh",
+                "marketpriceEurocentPerKWh": 20.0,
+            },
+        ],
+    }
+
+
+class TestFeedInTariffAkkudokor:
+
+    def test_provider_is_available(self, config_eos):
+        assert "FeedInTariffAkkudoktor" in config_eos.feedintariff.providers
+
+    def test_parse_data_uses_raw_market_price_without_import_charges(self, provider, response_data):
+        data = AkkudoktorElecPrice.model_validate(response_data)
+        series = provider._parse_data(data)
+        assert series.iloc[0] == pytest.approx(0.0001)
+
+    @pytest.mark.asyncio
+    async def test_hourly_prices_are_held_constant_on_quarter_hour_grid(self, provider, response_data):
+        data = AkkudoktorElecPrice.model_validate(response_data)
+        await provider.key_from_series("feed_in_tariff_wh", provider._parse_data(data))
+        start = to_datetime("2024-12-11 00:00:00", in_timezone="Europe/Berlin")
+
+        values = await provider.key_to_array(
+            key="feed_in_tariff_wh",
+            start_datetime=start,
+            end_datetime=start + to_duration("2 hours"),
+            interval=to_duration("15 minutes"),
+            fill_method="ffill",
+        )
+
+        assert values.tolist() == pytest.approx([0.0001] * 4 + [0.0002] * 4)
+
+    @patch("requests.get")
+    def test_request_uses_akkudoktor_prices_endpoint(self, mock_get, provider, response_data):
+        response = Mock()
+        response.content = json.dumps(response_data)
+        response.raise_for_status = Mock()
+        mock_get.return_value = response
+        get_ems().set_start_datetime(to_datetime("2024-12-11 00:00:00", in_timezone="Europe/Berlin"))
+
+        provider._request_forecast(force_update=True)
+
+        url = mock_get.call_args[0][0]
+        assert url.startswith("https://api.akkudoktor.net/prices?")
+        assert "tz=Europe/Berlin" in url
+        assert mock_get.call_args.kwargs["timeout"] == (5, 20)