feat(analytics): implement collection stats and floor price history

[aadviksinghdebug]

Summary

• Implements CollectionStats entity to store daily aggregated collection data (volume, floor price, sales count)
• Adds AnalyticsService with a midnight cron job that aggregates previous day's completed sales per collection by joining orders → nfts
• Floor price computed from minimum active listing price per collection
• Exposes GET /api/v1/collections/:id/stats?from=&to= returning both raw stats and chart-ready [timestamp, value] arrays
• Registers ScheduleModule.forRoot() via AnalyticsModule, enabling all existing cron jobs (listing expiry, auction settlement)

Changes

• src/modules/analytics/entities/collection-stats.entity.ts — new entity
• src/modules/analytics/analytics.service.ts — aggregation logic + cron job
• src/modules/analytics/analytics.controller.ts — stats endpoint
• src/modules/analytics/analytics.module.ts — module wiring
• src/app.module.ts — registers AnalyticsModule

Closes #83

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[aadviksinghdebug]

@Cedarich please review my PR

[aadviksinghdebug]

@Cedarich please review my PR

[aadviksinghdebug]

@Cedarich please review my PR