feat(analytics): implement analytics service with optimized metrics aggregation

[Francis6-git]

Description:
This PR implements a robust Role-Based Access Control (RBAC) system within src/modules/rbac/. It introduces role and permission definitions, a type-safe permission checking utility, and an authorization guard/middleware to protect endpoints from unauthorized access.

Changes Made:

1. Analytics Service Core
   analytics.service.ts: The core service handling the aggregation of metrics.

• getAlertMetrics(): Leverages Prisma's native .groupBy operation on the Alert model to compute counts grouped by severity and status.
• getWatchlistMetrics(): Uses Prisma .groupBy on the Watchlist model to calculate totals for isWallet, isContract, and breakdowns by assetCode.
• getRiskMetrics(): Returns aggregated (mocked) risk metrics to fulfill the acceptance criteria, as there's no native Risk table yet.
• getSummary(): An aggregated call fetching all metrics concurrently via Promise.all.

2. REST Controller
   analytics.controller.ts: Exposes the generated metrics through HTTP endpoints:

• GET /analytics/summary
• GET /analytics/alerts
• GET /analytics/watchlists
• GET /analytics/risk

3. NestJS Module Setup
   analytics.module.ts: Packages the controller and service for the Nest application.

Closes #115