Add blocked packages counter and storage progress bar

Backend:
- Add blocked_packages count to stats API by checking vulnerabilities against thresholds
- Add max_cache_size to stats API from config
- Add isBlocked field to package API responses

Frontend:
- Add blocked_packages and max_cache_size to Stats interface
- Add blocked packages counter card to stats page with fa-hand icon
- Add storage usage progress bar with color coding (green/yellow/orange/red)
- Add /blocked-packages route that filters vulnerable packages by isBlocked
- Update VulnerabilityBadge to show BLOCKED badge with fa-hand icon
- Fix TypeScript imports for useRoute in VulnerablePackages

Features:
- Stats page now shows blocked packages count (clickable)
- Storage display shows usage vs max with visual progress bar
- Blocked packages view accessible from stats page
- All blocked indicators use fa-hand icon instead of fa-ban

frontend/src/components/VulnerablePackages.vue

@@ -159,7 +159,7 @@
 
 <script setup lang="ts">
 import { computed, onMounted, ref } from 'vue'
-import { useRouter } from 'vue-router'
+import { useRouter, useRoute } from 'vue-router'
 import { usePackageStore, type Package } from '../stores/packages'
 import { Alert, AlertDescription } from '@/components/ui/alert'
 import { Card, CardContent } from '@/components/ui/card'

frontend/src/stores/packages.ts

@@ -34,9 +34,11 @@ export interface Stats {
   registry: string
   total_packages: number
   total_size: number
+  max_cache_size: number
   total_downloads: number
   scanned_packages: number
   vulnerable_packages: number
+  blocked_packages: number
 }
 
 export const usePackageStore = defineStore('packages', () => {