feat(pricing): implement tariff management with peak, valley, and flat pricing
feat(api): add tariff API for fetching and updating pricing configurations
feat(tariff-schema): create database schema for tariff configuration
feat(pricing-page): create UI for displaying and managing pricing tiers
fix(sidebar): update sidebar to include pricing settings link
feat(auth): implement login page and authentication middleware
feat(sidebar): create sidebar component with user info and navigation links
feat(api): establish API client for interacting with backend services
