Feature/v2/filemanagerimprovements (#4243)

- Select all/deselect all
- Delete Selected
- Download  Selected
- Recent file delete -> menu button with drop down for delete and
download
- Shift click selection added
<img width="1220" height="751"
alt="{330DF96D-7040-4CCB-B089-523F370E3185}"
src="https://github.com/user-attachments/assets/976e42cc-2124-4e62-83a8-25f184e8da3b"
/>
<img width="1160" height="749"
alt="{2D2F4876-7D35-45C3-B0CD-3127EEEEF7B5}"
src="https://github.com/user-attachments/assets/6879a174-a135-41f4-a876-984e7c2f96e2"
/>

---------

Co-authored-by: Connor Yoh <connor@stirlingpdf.com>

frontend/src/utils/downloadUtils.ts

@@ -0,0 +1,152 @@
+import { FileWithUrl } from '../types/file';
+import { fileStorage } from '../services/fileStorage';
+import { zipFileService } from '../services/zipFileService';
+
+/**
+ * Downloads a blob as a file using browser download API
+ * @param blob - The blob to download
+ * @param filename - The filename for the download
+ */
+export function downloadBlob(blob: Blob, filename: string): void {
+  const url = URL.createObjectURL(blob);
+  
+  const link = document.createElement('a');
+  link.href = url;
+  link.download = filename;
+  document.body.appendChild(link);
+  link.click();
+  document.body.removeChild(link);
+  
+  // Clean up the blob URL
+  URL.revokeObjectURL(url);
+}
+
+/**
+ * Downloads a single file from IndexedDB storage
+ * @param file - The file object with storage information
+ * @throws Error if file cannot be retrieved from storage
+ */
+export async function downloadFileFromStorage(file: FileWithUrl): Promise<void> {
+  const lookupKey = file.id || file.name;
+  const storedFile = await fileStorage.getFile(lookupKey);
+  
+  if (!storedFile) {
+    throw new Error(`File "${file.name}" not found in storage`);
+  }
+  
+  const blob = new Blob([storedFile.data], { type: storedFile.type });
+  downloadBlob(blob, storedFile.name);
+}
+
+/**
+ * Downloads multiple files as individual downloads
+ * @param files - Array of files to download
+ */
+export async function downloadMultipleFiles(files: FileWithUrl[]): Promise<void> {
+  for (const file of files) {
+    await downloadFileFromStorage(file);
+  }
+}
+
+/**
+ * Downloads multiple files as a single ZIP archive
+ * @param files - Array of files to include in ZIP
+ * @param zipFilename - Optional custom ZIP filename (defaults to timestamped name)
+ */
+export async function downloadFilesAsZip(files: FileWithUrl[], zipFilename?: string): Promise<void> {
+  if (files.length === 0) {
+    throw new Error('No files provided for ZIP download');
+  }
+
+  // Convert stored files to File objects
+  const fileObjects: File[] = [];
+  for (const fileWithUrl of files) {
+    const lookupKey = fileWithUrl.id || fileWithUrl.name;
+    const storedFile = await fileStorage.getFile(lookupKey);
+    
+    if (storedFile) {
+      const file = new File([storedFile.data], storedFile.name, {
+        type: storedFile.type,
+        lastModified: storedFile.lastModified
+      });
+      fileObjects.push(file);
+    }
+  }
+  
+  if (fileObjects.length === 0) {
+    throw new Error('No valid files found in storage for ZIP download');
+  }
+
+  // Generate default filename if not provided
+  const finalZipFilename = zipFilename || 
+    `files-${new Date().toISOString().slice(0, 19).replace(/[:-]/g, '')}.zip`;
+  
+  // Create and download ZIP
+  const { zipFile } = await zipFileService.createZipFromFiles(fileObjects, finalZipFilename);
+  downloadBlob(zipFile, finalZipFilename);
+}
+
+/**
+ * Smart download function that handles single or multiple files appropriately
+ * - Single file: Downloads directly
+ * - Multiple files: Downloads as ZIP
+ * @param files - Array of files to download
+ * @param options - Download options
+ */
+export async function downloadFiles(
+  files: FileWithUrl[], 
+  options: {
+    forceZip?: boolean;
+    zipFilename?: string;
+    multipleAsIndividual?: boolean;
+  } = {}
+): Promise<void> {
+  if (files.length === 0) {
+    throw new Error('No files provided for download');
+  }
+
+  if (files.length === 1 && !options.forceZip) {
+    // Single file download
+    await downloadFileFromStorage(files[0]);
+  } else if (options.multipleAsIndividual) {
+    // Multiple individual downloads
+    await downloadMultipleFiles(files);
+  } else {
+    // ZIP download (default for multiple files)
+    await downloadFilesAsZip(files, options.zipFilename);
+  }
+}
+
+/**
+ * Downloads a File object directly (for files already in memory)
+ * @param file - The File object to download
+ * @param filename - Optional custom filename
+ */
+export function downloadFileObject(file: File, filename?: string): void {
+  downloadBlob(file, filename || file.name);
+}
+
+/**
+ * Downloads text content as a file
+ * @param content - Text content to download
+ * @param filename - Filename for the download
+ * @param mimeType - MIME type (defaults to text/plain)
+ */
+export function downloadTextAsFile(
+  content: string, 
+  filename: string, 
+  mimeType: string = 'text/plain'
+): void {
+  const blob = new Blob([content], { type: mimeType });
+  downloadBlob(blob, filename);
+}
+
+/**
+ * Downloads JSON data as a file
+ * @param data - Data to serialize and download
+ * @param filename - Filename for the download
+ */
+export function downloadJsonAsFile(data: any, filename: string): void {
+  const content = JSON.stringify(data, null, 2);
+  downloadTextAsFile(content, filename, 'application/json');
+}