test: real backend pytest + E2E Playwright suites, both isolated from prod data

backend/tests/: 33 pytest tests against a real Postgres database
(aurum_test, created/migrated/dropped per run) exercised through the actual
HTTP API — not sqlite, not mocks, and the real `aurum` database is never
opened (app lifespan is skipped, get_session is overridden per test).
Covers transaction category-kind validation, year/month/date-range
filtering and pagination, dashboard summary arithmetic, budget status, cash
flow, and the /transactions/years picker.

e2e/: 6 Playwright specs driving a real browser against a fully separate
throwaway docker-compose stack (run.sh: separate project name, database,
port, and volume, torn down with `down -v` on exit) — regression coverage
for the Recent Transactions month bug, the Card grid-overflow bug, the
frozen-year bug, the Net Worth default range, and the Dashboard->
Transactions deep link, all fixed earlier this session.

Also synced the backend's APP_VERSION constant (stale at 0.15.2, embedded
in exported backups) with the frontend version.

backend/tests/test_dashboard.py

@@ -0,0 +1,110 @@
+"""Dashboard summary: the arithmetic and month-scoping behind the Overview
+page's four stat cards and the spending-by-category donut.
+"""
+from decimal import Decimal
+
+from httpx import AsyncClient
+
+from tests.helpers import money, txn_payload as _txn
+
+
+async def test_summary_is_zero_for_a_month_with_no_transactions(client: AsyncClient):
+    resp = await client.get("/dashboard/summary", params={"year": 2030, "month": 1})
+    body = resp.json()
+    assert money(body["real_income"]) == 0
+    assert money(body["spent"]) == 0
+    assert money(body["net"]) == 0
+    assert body["spending_by_category"] == []
+
+
+async def test_income_expense_and_net_only_count_the_selected_month(client: AsyncClient, account_id, categories):
+    groceries = categories["Groceries"]["id"]
+    salary = categories["Salary"]["id"]
+
+    # In scope: August 2026.
+    await client.post(
+        "/transactions", json=_txn(account_id, type="income", amount="3000.00", category_id=salary, date="2026-08-01")
+    )
+    await client.post(
+        "/transactions", json=_txn(account_id, type="expense", amount="1200.00", category_id=groceries, date="2026-08-20")
+    )
+    # Out of scope: same categories, different month — must not leak in.
+    await client.post(
+        "/transactions", json=_txn(account_id, type="income", amount="9999.00", category_id=salary, date="2026-07-31")
+    )
+    await client.post(
+        "/transactions", json=_txn(account_id, type="expense", amount="9999.00", category_id=groceries, date="2026-09-01")
+    )
+
+    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
+    body = resp.json()
+    assert money(body["real_income"]) == Decimal("3000.00")
+    assert money(body["spent"]) == Decimal("1200.00")
+    assert money(body["net"]) == Decimal("1800.00")
+
+
+async def test_transfers_are_excluded_from_income_and_spent(client: AsyncClient, account_id, categories):
+    other = await client.post("/accounts", json={"name": "Savings", "type": "savings", "currency": "USD"})
+    other_id = other.json()["id"]
+    await client.post(
+        "/transactions",
+        json=_txn(account_id, type="transfer", amount="500.00", transfer_account_id=other_id, date="2026-08-05"),
+    )
+    await client.post(
+        "/transactions",
+        json=_txn(account_id, type="income", amount="100.00", category_id=categories["Salary"]["id"], date="2026-08-05"),
+    )
+
+    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
+    body = resp.json()
+    assert money(body["real_income"]) == Decimal("100.00")
+    assert money(body["spent"]) == 0
+    assert money(body["transferred_out"]) == Decimal("500.00")
+
+
+async def test_spending_by_category_amounts_and_percent(client: AsyncClient, account_id, categories):
+    groceries = categories["Groceries"]["id"]
+    dining = categories["Dining Out"]["id"]
+    await client.post(
+        "/transactions", json=_txn(account_id, amount="75.00", category_id=groceries, date="2026-08-01")
+    )
+    await client.post(
+        "/transactions", json=_txn(account_id, amount="25.00", category_id=dining, date="2026-08-02")
+    )
+
+    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
+    breakdown = {row["name"]: row for row in resp.json()["spending_by_category"]}
+
+    assert money(breakdown["Groceries"]["amount"]) == Decimal("75.00")
+    assert breakdown["Groceries"]["percent"] == 75.0
+    assert money(breakdown["Dining Out"]["amount"]) == Decimal("25.00")
+    assert breakdown["Dining Out"]["percent"] == 25.0
+
+
+async def test_more_than_eight_expense_categories_roll_up_into_other(client: AsyncClient, account_id, categories):
+    expense_categories = [c for c in categories.values() if c["kind"] == "expense"]
+    # The default seed only ships 8 expense categories (see app/db/seed.py) —
+    # add a 9th ourselves rather than depending on that number ever changing.
+    extra = await client.post(
+        "/categories", json={"name": "Extra Expense", "kind": "expense", "color": "#123456", "sort_order": 99}
+    )
+    expense_categories.append(extra.json())
+    assert len(expense_categories) == 9
+
+    # Distinct amounts so we can tell which ones survive as their own slice.
+    for index, category in enumerate(expense_categories[:9]):
+        await client.post(
+            "/transactions",
+            json=_txn(account_id, amount=f"{(9 - index) * 10}.00", category_id=category["id"], date="2026-08-01"),
+        )
+
+    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
+    breakdown = resp.json()["spending_by_category"]
+
+    assert len(breakdown) == 9  # 8 explicit categories + one "Other" rollup
+    other = [row for row in breakdown if row["category_id"] is None]
+    assert len(other) == 1
+    assert other[0]["name"] == "Other"
+    # The 9th (smallest, index 8) category's 10.00 must be folded into Other,
+    # not silently dropped from the total.
+    assert money(other[0]["amount"]) == Decimal("10.00")