Enforce type checking in CI (#4126)

# Description of Changes
Currently, the `tsconfig.json` file enforces strict type checking, but
nothing in CI checks that the code is actually correctly typed. [Vite
only transpiles TypeScript
code](https://vite.dev/guide/features.html#transpile-only) so doesn't
ensure that the TS code we're running is correct.

This PR adds running of the type checker to CI and fixes the type errors
that have already crept into the codebase.

Note that many of the changes I've made to 'fix the types' are just
using `any` to disable the type checker because the code is under too
much churn to fix anything properly at the moment. I still think
enabling the type checker now is the best course of action though
because otherwise we'll never be able to fix all of them, and it should
at least help us not break things when adding new code.

Co-authored-by: James <james@crosscourtanalytics.com>

frontend/src/services/zipFileService.ts

@@ -1,4 +1,17 @@
-import JSZip from 'jszip';
+import JSZip, { JSZipObject } from 'jszip';
+
+// Undocumented interface in JSZip for JSZipObject._data
+interface CompressedObject {
+    compressedSize: number;
+    uncompressedSize: number;
+    crc32: number;
+    compression: object;
+    compressedContent: string|ArrayBuffer|Uint8Array|Buffer;
+}
+
+const getData = (zipEntry: JSZipObject): CompressedObject | undefined => {
+  return (zipEntry as any)._data as CompressedObject;
+}
 
 export interface ZipExtractionResult {
   success: boolean;
@@ -68,7 +81,7 @@ export class ZipFileService {
         }
 
         fileCount++;
-        const uncompressedSize = zipEntry._data?.uncompressedSize || 0;
+        const uncompressedSize = getData(zipEntry)?.uncompressedSize || 0;
         totalSize += uncompressedSize;
 
         // Check if file is a PDF
@@ -109,25 +122,25 @@ export class ZipFileService {
   async createZipFromFiles(files: File[], zipFilename: string): Promise<{ zipFile: File; size: number }> {
     try {
       const zip = new JSZip();
-      
+
       // Add each file to the ZIP
       for (const file of files) {
         const content = await file.arrayBuffer();
         zip.file(file.name, content);
       }
-      
+
       // Generate ZIP blob
-      const zipBlob = await zip.generateAsync({ 
+      const zipBlob = await zip.generateAsync({
         type: 'blob',
         compression: 'DEFLATE',
         compressionOptions: { level: 6 }
       });
-      
-      const zipFile = new File([zipBlob], zipFilename, { 
+
+      const zipFile = new File([zipBlob], zipFilename, {
         type: 'application/zip',
         lastModified: Date.now()
       });
-      
+
       return { zipFile, size: zipFile.size };
     } catch (error) {
       throw new Error(`Failed to create ZIP file: ${error instanceof Error ? error.message : 'Unknown error'}`);
@@ -162,7 +175,7 @@ export class ZipFileService {
       const zipContents = await zip.loadAsync(file);
 
       // Get all PDF files
-      const pdfFiles = Object.entries(zipContents.files).filter(([filename, zipEntry]) => 
+      const pdfFiles = Object.entries(zipContents.files).filter(([filename, zipEntry]) =>
         !zipEntry.dir && this.isPdfFile(filename)
       );
 
@@ -171,7 +184,7 @@ export class ZipFileService {
       // Extract each PDF file
       for (let i = 0; i < pdfFiles.length; i++) {
         const [filename, zipEntry] = pdfFiles[i];
-        
+
         try {
           // Report progress
           if (onProgress) {
@@ -185,9 +198,9 @@ export class ZipFileService {
 
           // Extract file content
           const content = await zipEntry.async('uint8array');
-          
+
           // Create File object
-          const extractedFile = new File([content], this.sanitizeFilename(filename), {
+          const extractedFile = new File([content as any], this.sanitizeFilename(filename), {
             type: 'application/pdf',
             lastModified: zipEntry.date?.getTime() || Date.now()
           });
@@ -235,7 +248,7 @@ export class ZipFileService {
 
     const validExtensions = ['.zip'];
     const hasValidType = validTypes.includes(file.type);
-    const hasValidExtension = validExtensions.some(ext => 
+    const hasValidExtension = validExtensions.some(ext =>
       file.name.toLowerCase().endsWith(ext)
     );
 
@@ -257,7 +270,7 @@ export class ZipFileService {
       // Read first few bytes to check PDF header
       const buffer = await file.slice(0, 8).arrayBuffer();
       const bytes = new Uint8Array(buffer);
-      
+
       // Check for PDF header: %PDF-
       return bytes[0] === 0x25 && // %
              bytes[1] === 0x50 && // P
@@ -275,7 +288,7 @@ export class ZipFileService {
   private sanitizeFilename(filename: string): string {
     // Remove directory path and get just the filename
     const basename = filename.split('/').pop() || filename;
-    
+
     // Remove or replace unsafe characters
     return basename
       .replace(/[<>:"/\\|?*]/g, '_') // Replace unsafe chars with underscore
@@ -309,15 +322,15 @@ export class ZipFileService {
     try {
       const zip = new JSZip();
       await zip.loadAsync(file);
-      
+
       // Check if any files are encrypted
       for (const [filename, zipEntry] of Object.entries(zip.files)) {
-        if (zipEntry.options?.compression === 'STORE' && zipEntry._data?.compressedSize === 0) {
+        if (zipEntry.options?.compression === 'STORE' && getData(zipEntry)?.compressedSize === 0) {
           // This might indicate encryption, but JSZip doesn't provide direct encryption detection
           // We'll handle this in the extraction phase
         }
       }
-      
+
       return false; // JSZip will throw an error if password is required
     } catch (error) {
       // If we can't load the ZIP, it might be password protected
@@ -328,4 +341,4 @@ export class ZipFileService {
 }
 
 // Export singleton instance
-export const zipFileService = new ZipFileService();
+export const zipFileService = new ZipFileService();