refactor: reorganize struct fields, add new handlers and storage backends

- [x] Reorder struct fields across codebase for consistency
- [x] Add analytics event handlers and tests
- [x] Add authentication API key management handlers and tests
- [x] Add pre-warming control handlers and tests
- [x] Implement S3 storage backend with tests
- [x] Implement SMB/CIFS storage backend with tests
- [x] Add CDN middleware tests
- [x] Integrate analytics tracking into cache manager
- [x] Add S3 and SMB storage initialization in app setup
- [x] Add CDN caching to proxy handlers
- [x] Remove distributed locking (Redis lock manager)
- [x] Remove proxy common package and utilities
- [x] Remove standalone HTTP server package
- [x] Remove logger middleware
- [x] Simplify error handling utilities
- [x] Update config with S3 and SMB options
- [x] Update cache manager signature to include analytics

pkg/metrics/metrics.go

@@ -137,21 +137,11 @@ func RecordCacheMiss(handler string) {
 	CacheRequests.WithLabelValues("miss", handler).Inc()
 }
 
-// RecordCacheError records a cache error
-func RecordCacheError(handler string) {
-	CacheRequests.WithLabelValues("error", handler).Inc()
-}
-
 // UpdateCacheSize updates the cache size metric
 func UpdateCacheSize(backend string, bytes int64) {
 	CacheSizeBytes.WithLabelValues(backend).Set(float64(bytes))
 }
 
-// UpdateCacheItems updates the cache items metric
-func UpdateCacheItems(handler string, count int64) {
-	CacheItemsTotal.WithLabelValues(handler).Set(float64(count))
-}
-
 // RecordCacheEviction records a cache eviction
 func RecordCacheEviction(reason string) {
 	CacheEvictions.WithLabelValues(reason).Inc()
@@ -162,26 +152,11 @@ func RecordStorageOperation(backend, operation, status string) {
 	StorageOperations.WithLabelValues(backend, operation, status).Inc()
 }
 
-// UpdateStorageQuota updates the storage quota metric
-func UpdateStorageQuota(project string, bytes int64) {
-	StorageQuotaBytes.WithLabelValues(project).Set(float64(bytes))
-}
-
 // RecordUpstreamRequest records an upstream request
 func RecordUpstreamRequest(registry, status string) {
 	UpstreamRequests.WithLabelValues(registry, status).Inc()
 }
 
-// RecordSecurityScan records a security scan
-func RecordSecurityScan(scanner, result string) {
-	SecurityScans.WithLabelValues(scanner, result).Inc()
-}
-
-// RecordVulnerability records a vulnerability finding
-func RecordVulnerability(severity string) {
-	VulnerabilitiesFound.WithLabelValues(severity).Inc()
-}
-
 // UpdateCircuitBreakerState updates the circuit breaker state
 func UpdateCircuitBreakerState(name string, state int) {
 	CircuitBreakerState.WithLabelValues(name).Set(float64(state))