V2 Make FileId type opaque and use consistently throughout project (#4307)

# Description of Changes
The `FileId` type in V2 currently is just defined to be a string. This
makes it really easy to accidentally pass strings into things accepting
file IDs (such as file names). This PR makes the `FileId` type [an
opaque
type](https://www.geeksforgeeks.org/typescript/opaque-types-in-typescript/),
so it is compatible with things accepting strings (arguably not ideal
for this...) but strings are not compatible with it without explicit
conversion.

The PR also includes changes to use `FileId` consistently throughout the
project (everywhere I could find uses of `fileId: string`), so that we
have the maximum benefit from the type safety.

> [!note]
> I've marked quite a few things as `FIX ME` where we're passing names
in as IDs. If that is intended behaviour, I'm happy to remove the fix me
and insert a cast instead, but they probably need comments explaining
why we're using a file name as an ID.

frontend/src/components/tools/convert/ConvertSettings.tsx

@@ -15,13 +15,14 @@ import ConvertFromWebSettings from "./ConvertFromWebSettings";
 import ConvertFromEmailSettings from "./ConvertFromEmailSettings";
 import ConvertToPdfaSettings from "./ConvertToPdfaSettings";
 import { ConvertParameters } from "../../../hooks/tools/convert/useConvertParameters";
-import { 
+import {
   FROM_FORMAT_OPTIONS,
   EXTENSION_TO_ENDPOINT,
   COLOR_TYPES,
   OUTPUT_OPTIONS,
   FIT_OPTIONS
 } from "../../../constants/convertConstants";
+import { FileId } from "../../../types/file";
 
 interface ConvertSettingsProps {
   parameters: ConvertParameters;
@@ -31,8 +32,8 @@ interface ConvertSettingsProps {
   disabled?: boolean;
 }
 
-const ConvertSettings = ({ 
-  parameters, 
+const ConvertSettings = ({
+  parameters,
   onParameterChange,
   getAvailableToExtensions,
   selectedFiles,
@@ -52,7 +53,7 @@ const ConvertSettings = ({
   const isConversionAvailable = (fromExt: string, toExt: string): boolean => {
     const endpointKey = EXTENSION_TO_ENDPOINT[fromExt]?.[toExt];
     if (!endpointKey) return false;
-    
+
     return endpointStatus[endpointKey] === true;
   };
 
@@ -61,10 +62,10 @@ const ConvertSettings = ({
     const baseOptions = FROM_FORMAT_OPTIONS.map(option => {
       // Check if this source format has any available conversions
       const availableConversions = getAvailableToExtensions(option.value) || [];
-      const hasAvailableConversions = availableConversions.some(targetOption => 
+      const hasAvailableConversions = availableConversions.some(targetOption =>
         isConversionAvailable(option.value, targetOption.value)
       );
-      
+
       return {
         ...option,
         enabled: hasAvailableConversions
@@ -80,18 +81,18 @@ const ConvertSettings = ({
         group: 'File',
         enabled: true
       };
-      
+
       // Add the dynamic option at the beginning
       return [dynamicOption, ...baseOptions];
     }
-    
+
     return baseOptions;
   }, [parameters.fromExtension, endpointStatus]);
 
-  // Enhanced TO options with endpoint availability  
+  // Enhanced TO options with endpoint availability
   const enhancedToOptions = useMemo(() => {
     if (!parameters.fromExtension) return [];
-    
+
     const availableOptions = getAvailableToExtensions(parameters.fromExtension) || [];
     return availableOptions.map(option => ({
       ...option,
@@ -131,7 +132,7 @@ const ConvertSettings = ({
     const files = activeFiles.map(fileId => selectors.getFile(fileId)).filter(Boolean) as File[];
     return files.filter(file => {
       const fileExtension = detectFileExtension(file.name);
-      
+
       if (extension === 'any') {
         return true;
       } else if (extension === 'image') {
@@ -148,15 +149,15 @@ const ConvertSettings = ({
       // Find the file ID by matching file properties
       const fileRecord = state.files.ids
         .map(id => selectors.getFileRecord(id))
-        .find(record => 
-          record && 
-          record.name === file.name && 
-          record.size === file.size && 
+        .find(record =>
+          record &&
+          record.name === file.name &&
+          record.size === file.size &&
           record.lastModified === file.lastModified
         );
       return fileRecord?.id;
-    }).filter((id): id is string => id !== undefined); // Type guard to ensure only strings
-    
+    }).filter((id): id is FileId => id !== undefined); // Type guard to ensure only strings
+
     setSelectedFiles(fileIds);
   };
 
@@ -164,7 +165,7 @@ const ConvertSettings = ({
     onParameterChange('fromExtension', value);
     setAutoTargetExtension(value);
     resetParametersToDefaults();
-    
+
     if (activeFiles.length > 0) {
       const matchingFiles = filterFilesByExtension(value);
       updateFileSelection(matchingFiles);
@@ -232,11 +233,11 @@ const ConvertSettings = ({
           >
             <Group justify="space-between">
               <Text size="sm">{t("convert.selectSourceFormatFirst", "Select a source format first")}</Text>
-              <KeyboardArrowDownIcon 
-                style={{ 
+              <KeyboardArrowDownIcon
+                style={{
                   fontSize: '1rem',
                   color: colorScheme === 'dark' ? theme.colors.dark[2] : theme.colors.gray[6]
-                }} 
+                }}
               />
             </Group>
           </UnstyledButton>
@@ -266,9 +267,9 @@ const ConvertSettings = ({
         </>
       )}
 
-      
+
       {/* Color options for image to PDF conversion */}
-      {(isImageFormat(parameters.fromExtension) && parameters.toExtension === 'pdf') || 
+      {(isImageFormat(parameters.fromExtension) && parameters.toExtension === 'pdf') ||
        (parameters.isSmartDetection && parameters.smartDetectionType === 'images') ? (
         <>
           <Divider />
@@ -281,7 +282,7 @@ const ConvertSettings = ({
       ) : null}
 
       {/* Web to PDF options */}
-      {((isWebFormat(parameters.fromExtension) && parameters.toExtension === 'pdf') || 
+      {((isWebFormat(parameters.fromExtension) && parameters.toExtension === 'pdf') ||
        (parameters.isSmartDetection && parameters.smartDetectionType === 'web')) ? (
         <>
           <Divider />
@@ -322,4 +323,4 @@ const ConvertSettings = ({
   );
 };
 
-export default ConvertSettings;
+export default ConvertSettings;