refactor(import): Implement DownloadManager, FolderBrowser, ImageProcessor, and RecipeDataManager for enhanced recipe import functionality

- Added DownloadManager to handle saving recipes and downloading missing LoRAs.
- Introduced FolderBrowser for selecting LoRA root directories and managing folder navigation.
- Created ImageProcessor for handling image uploads and URL inputs for recipe analysis.
- Developed RecipeDataManager to manage recipe details, including metadata and LoRA information.
- Implemented ImportStepManager to control the flow of the import process and manage UI steps.
- Added utility function for formatting file sizes for better user experience.

static/js/managers/import/ImportStepManager.js

@@ -0,0 +1,57 @@
+export class ImportStepManager {
+    constructor() {
+        this.injectedStyles = null;
+    }
+
+    removeInjectedStyles() {
+        if (this.injectedStyles && this.injectedStyles.parentNode) {
+            this.injectedStyles.parentNode.removeChild(this.injectedStyles);
+            this.injectedStyles = null;
+        }
+        
+        // Reset inline styles
+        document.querySelectorAll('.import-step').forEach(step => {
+            step.style.cssText = '';
+        });
+    }
+
+    showStep(stepId) {
+        // Remove any injected styles to prevent conflicts
+        this.removeInjectedStyles();
+        
+        // Hide all steps first
+        document.querySelectorAll('.import-step').forEach(step => {
+            step.style.display = 'none';
+        });
+        
+        // Show target step with a monitoring mechanism
+        const targetStep = document.getElementById(stepId);
+        if (targetStep) {
+            // Use direct style setting
+            targetStep.style.display = 'block';
+            
+            // For the locationStep specifically, we need additional measures
+            if (stepId === 'locationStep') {
+                // Create a more persistent style to override any potential conflicts
+                this.injectedStyles = document.createElement('style');
+                this.injectedStyles.innerHTML = `
+                    #locationStep {
+                        display: block !important;
+                        opacity: 1 !important;
+                        visibility: visible !important;
+                    }
+                `;
+                document.head.appendChild(this.injectedStyles);
+                
+                // Force layout recalculation
+                targetStep.offsetHeight;
+            }
+            
+            // Scroll modal content to top
+            const modalContent = document.querySelector('#importModal .modal-content');
+            if (modalContent) {
+                modalContent.scrollTop = 0;
+            }
+        }
+    }
+}