Implement backend API and database services in Docker setup

- Added a new `api` service for the NestJS backend, including health checks and dependencies on PostgreSQL, Redis, and MinIO.
- Introduced PostgreSQL and Redis services with health checks and configurations for data persistence.
- Added MinIO for S3-compatible object storage and a one-shot service to initialize required buckets.
- Updated the Nginx configuration to proxy requests to the new backend API and MinIO storage.
- Enhanced the Dockerfile to support the new API environment variables and configurations.
- Updated the `package.json` and `package-lock.json` to include new dependencies for QR code generation and other utilities.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/utils/mock.ts

@@ -0,0 +1,63 @@
+/**
+ * Centralised mock-mode flag.
+ *
+ * Rules:
+ *  1. VITE_USE_MOCK_DATA="true"  → mock ON
+ *  2. VITE_USE_MOCK_DATA="false" → mock OFF (try real backend)
+ *  3. Unset / empty              → fall back to import.meta.env.DEV
+ *
+ * If the user opted for real mode (rule 2) but the backend is
+ * unreachable, `initMockMode()` automatically flips USE_MOCK to
+ * true so the app remains usable.  A console banner lets the dev
+ * know what happened.
+ */
+
+const explicit = import.meta.env.VITE_USE_MOCK_DATA
+
+// Exported as `let` so initMockMode() can reassign it.
+// ES module live-bindings ensure every importer sees the update.
+export let USE_MOCK: boolean =
+  explicit === 'false'
+    ? false
+    : explicit === 'true'
+      ? true
+      : import.meta.env.DEV
+
+/**
+ * Call once at app startup (before mounting).
+ * Pings the backend — if unreachable and USE_MOCK is false,
+ * flips USE_MOCK to true so the whole app falls back to mock data.
+ */
+export async function initMockMode(): Promise<void> {
+  // Nothing to check if mock is already on
+  if (USE_MOCK) return
+
+  const apiUrl = import.meta.env.VITE_API_URL || 'http://localhost:4000'
+
+  try {
+    const controller = new AbortController()
+    const timeout = setTimeout(() => controller.abort(), 2000)
+
+    await fetch(apiUrl, {
+      method: 'HEAD',
+      signal: controller.signal,
+    })
+
+    clearTimeout(timeout)
+    // Backend is reachable — keep USE_MOCK = false
+    console.log(
+      '%c✅ Backend connected at %s — real mode active',
+      'color: #22c55e; font-weight: bold',
+      apiUrl,
+    )
+  } catch {
+    // Backend is not reachable — flip to mock
+    USE_MOCK = true
+    console.warn(
+      '%c⚠️ Backend not reachable at %s — auto-switching to mock mode.\n' +
+      '   Start the backend (npm run dev:full) for real API/payments.',
+      'color: #f59e0b; font-weight: bold',
+      apiUrl,
+    )
+  }
+}