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.

e2e/tests/dashboard-long-description-no-overflow.spec.ts

@@ -0,0 +1,60 @@
+import { test, expect } from "@playwright/test";
+import { createTransaction, getCategoryId, getDefaultAccountId } from "./helpers";
+
+// Regression for v0.15.4: a transaction description with no spaces (so it
+// can't wrap) blew out the Dashboard's CSS Grid because Card had no
+// min-width: 0, growing the whole page wider than the viewport instead of
+// letting `truncate` ellipsize the text. See UPDATES.md (v0.15.4) and
+// frontend/src/components/ui/Card.tsx.
+const LONG_DESCRIPTION =
+  "оченьдлинноеописаниебезпробеловкотороедолжнообрезатьсямноготочиемачтобынеломатьверсткукарточкинадашборде1234567890";
+
+test("a long unbroken transaction description never causes horizontal page overflow", async ({ page, request }) => {
+  const accountId = await getDefaultAccountId(request);
+  const categoryId = await getCategoryId(request, "Groceries");
+  await createTransaction(request, {
+    account_id: accountId,
+    category_id: categoryId,
+    type: "expense",
+    amount: "12.34",
+    description: LONG_DESCRIPTION,
+    date: "2016-08-01",
+  });
+
+  await page.goto("/");
+  await page.getByRole("button", { name: /^\d{4}$/ }).first().click();
+  await page.getByRole("option", { name: "2016" }).click();
+  await page.getByRole("button", { name: "Авг", exact: true }).click();
+  await expect(page.getByText(LONG_DESCRIPTION.slice(0, 20), { exact: false })).toBeVisible();
+
+  const overflow = await page.evaluate(() => ({
+    scrollWidth: document.documentElement.scrollWidth,
+    clientWidth: document.documentElement.clientWidth,
+  }));
+  expect(overflow.scrollWidth).toBeLessThanOrEqual(overflow.clientWidth);
+});
+
+test("same check on a narrow mobile viewport", async ({ page, request }) => {
+  await page.setViewportSize({ width: 375, height: 812 });
+  const accountId = await getDefaultAccountId(request);
+  const categoryId = await getCategoryId(request, "Groceries");
+  await createTransaction(request, {
+    account_id: accountId,
+    category_id: categoryId,
+    type: "expense",
+    amount: "12.34",
+    description: LONG_DESCRIPTION,
+    date: "2016-09-01",
+  });
+
+  await page.goto("/");
+  await page.getByRole("button", { name: /^\d{4}$/ }).first().click();
+  await page.getByRole("option", { name: "2016" }).click();
+  await page.getByRole("button", { name: "Сен", exact: true }).click();
+
+  const overflow = await page.evaluate(() => ({
+    scrollWidth: document.documentElement.scrollWidth,
+    clientWidth: document.documentElement.clientWidth,
+  }));
+  expect(overflow.scrollWidth).toBeLessThanOrEqual(overflow.clientWidth);
+});