Implement Statistics View with Real Charts

[DrunkOnJava]

📋 Sub-task of #106

Description

Replace placeholder chart in Statistics View with real data visualizations using SwiftUI Charts.

Current State

// Placeholder implementation
Text("📊 Chart placeholder")
    .font(.largeTitle)
    .foregroundColor(.secondary)

Required Implementation

• Total inventory value over time chart
• Items by category pie chart
• Monthly spending trends
• Most valuable items list
• Location distribution map
• Purchase patterns analysis

Chart Types Needed

1. Line Chart: Value trends over time
2. Pie Chart: Category distribution
3. Bar Chart: Monthly comparisons
4. Heat Map: Purchase patterns

Technical Requirements

• Use SwiftUI Charts (iOS 16+)
• Implement data aggregation in ViewModel
• Add date range selector
• Support different time periods (week/month/year)
• Animate chart transitions
• Export chart as image

Data Processing

• Create StatisticsService for data aggregation
• Implement efficient queries for large datasets
• Add caching for computed values
• Background processing for heavy calculations

UI/UX Requirements

• Interactive charts with tap details
• Smooth animations
• Color-coded categories
• Legend with totals
• Pull-to-refresh
• Loading states while calculating

Files to Update

• Modules/Core/Sources/Views/Statistics/StatisticsView.swift
• Create: Modules/Core/Sources/Services/StatisticsService.swift
• Create: Modules/Core/Sources/ViewModels/StatisticsViewModel.swift

Estimated Effort: 4-5 days

[DrunkOnJava]

Closing: This issue has been resolved/superseded by the complete modular architecture restructure now in main branch (commit 33a0ead). The new architecture implements a comprehensive solution that addresses the core needs this issue was tracking.