feat: implement database backup and restore functionality in settings page

- Added UI components for downloading and restoring the application database, enhancing data management capabilities.
- Integrated new API routes for system database operations in the backend.
- Implemented state management for backup and restore processes, including loading indicators and user notifications.

backend/src/routes/system-database.ts

@@ -0,0 +1,73 @@
+import type { FastifyPluginAsync } from "fastify"
+import { appendEvent } from "../modules/events/service/events-service.js"
+import {
+  exportSystemDatabaseBackup,
+  getSystemDatabasePath,
+  restoreSystemDatabaseBackup,
+} from "../services/system-database-backup.js"
+
+const systemDatabaseRoutes: FastifyPluginAsync = async (app) => {
+  app.addContentTypeParser(
+    "application/octet-stream",
+    { parseAs: "buffer", bodyLimit: 512 * 1024 * 1024 },
+    (_req, body, done) => {
+      done(null, body)
+    },
+  )
+
+  app.get("/system/database/backup", async (_req, reply) => {
+    try {
+      const { filename, buffer } = await exportSystemDatabaseBackup()
+      appendEvent({
+        level: "info",
+        eventType: "system.database.backup",
+        sourceModule: "system",
+        title: "Создан бэкап базы приложения",
+        message: filename,
+        entityType: "system_database",
+        entityId: filename,
+        payload: {
+          filename,
+          sizeBytes: buffer.length,
+          databasePath: getSystemDatabasePath(),
+        },
+      })
+      reply.header("Content-Type", "application/octet-stream")
+      reply.header("Content-Disposition", `attachment; filename="${filename}"`)
+      return reply.send(buffer)
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err)
+      return reply.status(500).send({ error: message })
+    }
+  })
+
+  app.post("/system/database/restore", async (req, reply) => {
+    const body = req.body
+    if (!Buffer.isBuffer(body) || body.length === 0) {
+      return reply.status(400).send({ error: "Ожидается тело запроса с файлом SQLite" })
+    }
+    try {
+      await restoreSystemDatabaseBackup(body)
+      appendEvent({
+        level: "warning",
+        eventType: "system.database.restore",
+        sourceModule: "system",
+        title: "Восстановлена база приложения",
+        message: "Данные SQLite заменены из загруженного файла",
+        entityType: "system_database",
+        entityId: "restore",
+        payload: {
+          sizeBytes: body.length,
+          databasePath: getSystemDatabasePath(),
+        },
+      })
+      return reply.send({ ok: true })
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err)
+      const status = message.includes("уже выполняется") ? 409 : 400
+      return reply.status(status).send({ error: message })
+    }
+  })
+}
+
+export default systemDatabaseRoutes