feat(analytics): доходы, ребалансировка, налоги, бенчмарки и цели — фаза 4

Второй источник выплат: sources/tinvest/sync_events.py (GetDividends,
GetBondCoupons, GetBondEvents) и sources/moex/payouts.py (ISS bondization +
dividends). Приоритет между ними — pricing/payouts.resolve_payouts, решается
на чтении, а не на записи: corporate_action уникален по (instrument_id, kind,
source, source_id), обе версии сосуществуют, и правило можно поменять без
ресинка истории. Амортизация от MOEX идёт в bond_nominal_schedule, а не
в corporate_action — этим типом безраздельно владеет
ledger/corporate_actions.py.

analytics/income.py — metric_income_monthly (факт) и metric_income_calendar
(прошлое и прогноз) с basis paid/announced/history на каждой строке, три
источника числа не смешиваются. analytics/rebalance.py — сделки по
portfolio_target пропорционально внутри бакета, лоты только вниз, покупки не
занимают у ещё не свершившихся продаж. analytics/tax.py — оценка, не замена
справки брокера: дивиденды/купоны gross, реализованный результат из
lot_disposal с переоценкой каждой ноги на свою дату. analytics/benchmarks.py —
TWR индекса на сетке портфеля, kind (price/total_return) не скрывается.
analytics/goals.py — прогресс цели и нужный взнос по trailing XIRR.

Четыре шага зарегистрированы в register_steps: benchmarks после returns
(общая сетка дат), rebalance после allocation (её веса, не пересчитывает),
income и tax после lots (нужен lot_disposal).

backend/tests/api/test_tax_api.py

@@ -0,0 +1,144 @@
+"""`GET /tax` and `GET /tax/lots` — the screen that prices selling before the three-year mark.
+
+The router is not wired into `api/app.py` by this module's author, so the tests mount it on a
+copy of the application. That keeps the check honest about the routes' own behaviour while
+leaving the inclusion order to whoever owns `app.py`.
+"""
+
+import json
+from collections.abc import AsyncIterator
+from datetime import timedelta
+from decimal import Decimal
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from factories import make_account, make_event, make_instrument, make_price
+from fintracker.analytics import today_local
+from fintracker.analytics.tax import rebuild_tax_year
+from fintracker.api.routers import tax as tax_router
+from fintracker.db import get_sessionmaker
+from fintracker.ledger.rebuild import rebuild_lots
+from fintracker.models import AccountKind, AccountRole, AssetClass, EventKind
+from fintracker.pricing.fx import rebuild_fx_daily
+
+D = Decimal
+LDV_DAYS = 3 * 365
+
+
+@pytest.fixture
+async def tax_client(app, auth_headers) -> AsyncIterator[AsyncClient]:
+    """The application plus the tax router, which `app.py` does not include yet."""
+    app.include_router(tax_router.router, prefix="/api/v1")
+    async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as c:
+        c.headers.update(auth_headers)
+        yield c
+
+
+@pytest.fixture
+async def lots(app) -> dict[str, object]:
+    """Two open lots of the same paper: one past the ЛДВ mark, one still short of it."""
+    t = today_local()
+    old_date = t - timedelta(days=LDV_DAYS + 30)
+    young_date = t - timedelta(days=400)
+
+    account = await make_account(
+        name="ИИС",
+        kind=AccountKind.broker,
+        role=AccountRole.investment,
+        balance=None,
+        include_in_net_worth=False,
+        source="tinvest",
+    )
+    old_share = await make_instrument(ticker="SBER", name="Сбербанк", asset_class=AssetClass.share)
+    young_share = await make_instrument(ticker="GAZP", name="Газпром", asset_class=AssetClass.share)
+    await make_event(
+        old_date,
+        account_id=account,
+        kind=EventKind.buy,
+        instrument_id=old_share,
+        quantity="10",
+        price="100",
+        amount="-1000",
+    )
+    await make_event(
+        young_date,
+        account_id=account,
+        kind=EventKind.buy,
+        instrument_id=young_share,
+        quantity="20",
+        price="240",
+        amount="-4800",
+    )
+    await make_price(t, instrument_id=old_share, close="150")
+    await make_price(t, instrument_id=young_share, close="275.89")
+
+    async with get_sessionmaker()() as session:
+        await rebuild_fx_daily(session)
+        await session.commit()
+        await rebuild_lots(session)
+        await session.commit()
+        await rebuild_tax_year(session)
+        await session.commit()
+    return {
+        "account": account,
+        "old": old_share,
+        "young": young_share,
+        "old_date": old_date,
+        "young_date": young_date,
+        "today": t,
+    }
+
+
+async def test_lots_show_the_days_left_to_the_exemption(tax_client, lots):
+    r = await tax_client.get("/api/v1/tax/lots")
+    assert r.status_code == 200, r.text
+    body = r.json()
+    assert body["estimated"] is True
+    assert body["tax_rate"] == "0.13"
+    assert body["disclaimer"]
+
+    by_ticker = {lot["ticker"]: lot for lot in body["lots"]}
+    young = by_ticker["GAZP"]
+    ldv_date = lots["young_date"] + timedelta(days=LDV_DAYS)
+    assert young["ldv_date"] == ldv_date.isoformat()
+    assert young["days_to_ldv"] == (ldv_date - lots["today"]).days
+    assert young["ldv_eligible"] is False
+    # 20 x 275.89 = 5517.80 against a cost of 4800 -> 717.80 unrealised, 13 % of it is 93.31
+    assert young["market_value_rub"] == "5517.80"
+    assert young["cost_rub"] == "4800.00"
+    assert young["unrealized_gain_rub"] == "717.80"
+    assert young["tax_if_sold_now_rub"] == "93.31"
+
+
+async def test_a_lot_past_three_years_costs_nothing_to_sell(tax_client, lots):
+    body = (await tax_client.get("/api/v1/tax/lots")).json()
+    old = {lot["ticker"]: lot for lot in body["lots"]}["SBER"]
+
+    assert old["ldv_eligible"] is True
+    assert old["days_to_ldv"] == 0
+    # 10 x 150 = 1500 against 1000 is a real gain, and art. 219.1 makes it untaxed
+    assert old["unrealized_gain_rub"] == "500.00"
+    assert old["tax_if_sold_now_rub"] == "0.00"
+
+
+async def test_the_year_summary_is_marked_an_estimate(tax_client, lots):
+    r = await tax_client.get("/api/v1/tax", params={"year": lots["today"].year})
+    assert r.status_code == 200, r.text
+    body = r.json()
+    assert body["estimated"] is True
+    assert body["tax_rate"] == "0.13"
+    assert "брокер" in body["disclaimer"]
+    # nothing was sold, so the year is empty — but it is still a well-formed answer
+    assert body["totals"]["estimated_tax_rub"] == "0.00"
+    assert body["accounts"] == []
+
+
+async def test_no_float_reaches_the_wire(tax_client, lots):
+    def reject_float(raw: str) -> None:
+        raise AssertionError(f"float in the response: {raw}")
+
+    for path in ("/api/v1/tax", "/api/v1/tax/lots"):
+        r = await tax_client.get(path)
+        assert r.status_code == 200, r.text
+        json.loads(r.text, parse_float=reject_float)