refactor(router): update routes and middleware for Echo v5

Update all router files to use Echo v5 APIs and type signatures.

Changes in router.go:
- Replace echomiddleware.Logger() with RequestLogger() (line 144)
- Update import from echo/v4 to echo/v5

Changes in frontend.go:
- Update frontend handler signatures to use *echo.Context
- Fix middleware registration for v5 compatibility

Changes in auth.go, library.go, scanner.go, sync.go, helpers.go:
- Update handler function signatures to *echo.Context
- Ensure consistent type usage across all route handlers

All routes now properly implement Echo v5's middleware and handler patterns.

internal/router/sync.go

@@ -43,6 +43,6 @@ func registerSyncRoutes(cfg *Config) {
 func registerWebSocketRoutes(cfg *Config) {
 	e := cfg.Echo
 
-	// WebSocket endpoint for real-time sync
-	e.GET("/ws/sync", cfg.WSHandler.HandleWebSocket)
+	wsGroup := e.Group("/ws/sync")
+	wsGroup.GET("", cfg.WSHandler.HandleWebSocket)
 }