Feature/v2/file handling improvements (#4222)

# Description of Changes

A new universal file context rather than the splintered ones for the
main views, tools and manager we had before (manager still has its own
but its better integreated with the core context)
File context has been split it into a handful of different files
managing various file related issues separately to reduce the monolith -
FileReducer.ts - State management
  fileActions.ts - File operations
  fileSelectors.ts - Data access patterns
  lifecycle.ts - Resource cleanup and memory management
  fileHooks.ts - React hooks interface
  contexts.ts - Context providers
Improved thumbnail generation
Improved indexxedb handling
Stopped handling files as blobs were not necessary to improve
performance
A new library handling drag and drop
https://github.com/atlassian/pragmatic-drag-and-drop (Out of scope yes
but I broke the old one with the new filecontext and it needed doing so
it was a might as well)
A new library handling virtualisation on page editor
@tanstack/react-virtual, as above.
Quickly ripped out the last remnants of the old URL params stuff and
replaced with the beginnings of what will later become the new URL
navigation system (for now it just restores the tool name in url
behavior)
Fixed selected file not regestered when opening a tool
Fixed png thumbnails
Closes #(issue_number)

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: Reece Browne <you@example.com>

frontend/src/utils/fileUtils.ts

@@ -1,9 +1,4 @@
-import { FileWithUrl } from "../types/file";
-import { StoredFile, fileStorage } from "../services/fileStorage";
-
-export function getFileId(file: File): string | null {
-  return (file as File & { id?: string }).id || null;
-}
+// Pure utility functions for file operations
 
 /**
  * Consolidated file size formatting utility
@@ -19,7 +14,7 @@ export function formatFileSize(bytes: number): string {
 /**
  * Get file date as string
  */
-export function getFileDate(file: File): string {
+export function getFileDate(file: File | { lastModified: number }): string {
   if (file.lastModified) {
     return new Date(file.lastModified).toLocaleString();
   }
@@ -29,107 +24,12 @@ export function getFileDate(file: File): string {
 /**
  * Get file size as string (legacy method for backward compatibility)
  */
-export function getFileSize(file: File): string {
+export function getFileSize(file: File | { size: number }): string {
   if (!file.size) return "Unknown";
   return formatFileSize(file.size);
 }
 
-/**
- * Create enhanced file object from stored file metadata
- * This eliminates the repeated pattern in FileManager
- */
-export function createEnhancedFileFromStored(storedFile: StoredFile, thumbnail?: string): FileWithUrl {
-  const enhancedFile: FileWithUrl = {
-    id: storedFile.id,
-    storedInIndexedDB: true,
-    url: undefined, // Don't create blob URL immediately to save memory
-    thumbnail: thumbnail || storedFile.thumbnail,
-    // File metadata
-    name: storedFile.name,
-    size: storedFile.size,
-    type: storedFile.type,
-    lastModified: storedFile.lastModified,
-    webkitRelativePath: '',
-    // Lazy-loading File interface methods
-    arrayBuffer: async () => {
-      const data = await fileStorage.getFileData(storedFile.id);
-      if (!data) throw new Error(`File ${storedFile.name} not found in IndexedDB - may have been purged`);
-      return data;
-    },
-    bytes: async () => {
-      return new Uint8Array();
-    },
-    slice: (start?: number, end?: number, contentType?: string) => {
-      // Return a promise-based slice that loads from IndexedDB
-      return new Blob([], { type: contentType || storedFile.type });
-    },
-    stream: () => {
-      throw new Error('Stream not implemented for IndexedDB files');
-    },
-    text: async () => {
-      const data = await fileStorage.getFileData(storedFile.id);
-      if (!data) throw new Error(`File ${storedFile.name} not found in IndexedDB - may have been purged`);
-      return new TextDecoder().decode(data);
-    },
-  } as FileWithUrl;
 
-  return enhancedFile;
-}
-
-/**
- * Load files from IndexedDB and convert to enhanced file objects
- */
-export async function loadFilesFromIndexedDB(): Promise<FileWithUrl[]> {
-  try {
-    await fileStorage.init();
-    const storedFiles = await fileStorage.getAllFileMetadata();
-
-    if (storedFiles.length === 0) {
-      return [];
-    }
-
-    const restoredFiles: FileWithUrl[] = storedFiles
-      .filter(storedFile => {
-        // Filter out corrupted entries
-        return storedFile &&
-               storedFile.name &&
-               typeof storedFile.size === 'number';
-      })
-      .map(storedFile => {
-        try {
-          return createEnhancedFileFromStored(storedFile as any);
-        } catch (error) {
-          console.error('Failed to restore file:', storedFile?.name || 'unknown', error);
-          return null;
-        }
-      })
-      .filter((file): file is FileWithUrl => file !== null);
-
-    return restoredFiles;
-  } catch (error) {
-    console.error('Failed to load files from IndexedDB:', error);
-    return [];
-  }
-}
-
-/**
- * Clean up blob URLs from file objects
- */
-export function cleanupFileUrls(files: FileWithUrl[]): void {
-  files.forEach(file => {
-    if (file.url && !file.url.startsWith('indexeddb:')) {
-      URL.revokeObjectURL(file.url);
-    }
-  });
-}
-
-/**
- * Check if file should use blob URL or IndexedDB direct access
- */
-export function shouldUseDirectIndexedDBAccess(file: FileWithUrl): boolean {
-  const FILE_SIZE_LIMIT = 100 * 1024 * 1024; // 100MB
-  return file.size > FILE_SIZE_LIMIT;
-}
 
 /**
  * Detects and normalizes file extension from filename
@@ -151,29 +51,3 @@ export function detectFileExtension(filename: string): string {
 
   return extension;
 }
-
-/**
- * Gets the filename without extension
- * @param filename - The filename to process
- * @returns Filename without extension
- */
-export function getFilenameWithoutExtension(filename: string): string {
-  if (!filename || typeof filename !== 'string') return '';
-
-  const parts = filename.split('.');
-  if (parts.length <= 1) return filename;
-
-  // Return all parts except the last one (extension)
-  return parts.slice(0, -1).join('.');
-}
-
-/**
- * Creates a new filename with a different extension
- * @param filename - Original filename
- * @param newExtension - New extension (without dot)
- * @returns New filename with the specified extension
- */
-export function changeFileExtension(filename: string, newExtension: string): string {
-  const nameWithoutExt = getFilenameWithoutExtension(filename);
-  return `${nameWithoutExt}.${newExtension}`;
-}