test: migrate e2e to Playwright and component test to Vitest browser mode

Replace Cypress with Playwright for the end-to-end suite and drop
@shellygo/cypress-test-utils in favour of a hand-written MaputnikDriver
page object that keeps the fluent then(...).shouldX() assertion style
(now async). The InputAutocomplete component test moves to Vitest browser
mode using the Playwright provider.

- e2e/maputnik-driver.ts: driver + MaputnikAssertable over Playwright
- e2e/{fixtures,coverage,global-setup,global-teardown}.ts: test fixture,
  istanbul coverage collection, and nyc report generation
- playwright.config.ts / vitest.config.ts
- Code coverage preserved: dev server is istanbul-instrumented, per-test
  window.__coverage__ is merged via nyc into coverage/coverage-final.json
- CI: Cypress jobs replaced with Playwright; docker e2e runs against the
  container via E2E_NO_WEBSERVER
- Remove Cypress deps, config and support files; update docs and .nycrc

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

e2e/global-teardown.ts

@@ -0,0 +1,23 @@
+import fs from "node:fs";
+import path from "node:path";
+import { execFileSync } from "node:child_process";
+
+/**
+ * Merges the per-test istanbul coverage chunks collected in `.nyc_output` into a
+ * report (configured by `.nycrc.json`) once the whole e2e run has finished.
+ */
+export default function globalTeardown(): void {
+  const dir = path.resolve(process.cwd(), ".nyc_output");
+  const hasCoverage = fs.existsSync(dir) && fs.readdirSync(dir).some((f) => f.endsWith(".json"));
+  if (!hasCoverage) {
+    console.warn("No coverage data collected; skipping coverage report.");
+    return;
+  }
+  try {
+    execFileSync("npx", ["nyc", "report"], { stdio: "inherit" });
+  } catch (error) {
+    // Don't fail the whole run if the report can't be generated (e.g. when
+    // running against a container whose source paths differ from the host).
+    console.warn("Failed to generate coverage report:", error);
+  }
+}