feat: Add comprehensive backend validation, toast notifications, and Tokyo Night theme

- Backend: Add server-side validation with go-playground/validator/v10
- Frontend: Add toast notifications for API errors with @zerodevx/svelte-toast
- UI: Complete Tokyo Night theme redesign with modern animations
- Docs: Update COMPLETE_DOCUMENTATION.md and README.md with all enhancements
- Validation: Email format, password strength, and input sanitization
- UX: Real-time error feedback, loading states, and responsive design

docker-compose.yml

@@ -0,0 +1,51 @@
+version: "3.8"
+
+services:
+  db:
+    image: postgres:15-alpine
+    environment:
+      POSTGRES_DB: ebookdb
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: ${DBPASS}
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+      - ./backend/migrations:/docker-entrypoint-initdb.d
+    ports:
+      - "5432:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+    env_file:
+      - .env
+
+  backend:
+    build:
+      context: .
+      dockerfile: ./backend/Dockerfile
+    environment:
+      DATABASE_HOST: db
+      DATABASE_PORT: 5432
+      DATABASE_USER: postgres
+      DATABASE_PASSWORD: ${DBPASS}
+      DATABASE_NAME: ebookdb
+      JWT_SECRET: ${JWT_SECRET}
+      SERVER_PORT: 8765
+    ports:
+      - "8765:8765"
+    depends_on:
+      db:
+        condition: service_healthy
+    volumes:
+      - ./backend/uploads:/app/uploads
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8765/"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+    env_file:
+      - .env
+
+volumes:
+  postgres_data: