Restructure frontend code to allow for extensions (#4721)

# Description of Changes
Move frontend code into `core` folder and add infrastructure for
`proprietary` folder to include premium, non-OSS features

frontend/src/core/utils/convertUtils.ts

@@ -0,0 +1,90 @@
+import { 
+  CONVERSION_ENDPOINTS,
+  ENDPOINT_NAMES,
+  EXTENSION_TO_ENDPOINT,
+  CONVERSION_MATRIX,
+  TO_FORMAT_OPTIONS
+} from '@app/constants/convertConstants';
+
+/**
+ * Resolves the endpoint name for a given conversion
+ */
+export const getEndpointName = (fromExtension: string, toExtension: string): string => {
+  if (!fromExtension || !toExtension) return '';
+  
+  let endpointKey = EXTENSION_TO_ENDPOINT[fromExtension]?.[toExtension];
+  
+  // If no explicit mapping exists and we're converting to PDF, 
+  // fall back to 'any' which uses file-to-pdf endpoint
+  if (!endpointKey && toExtension === 'pdf' && fromExtension !== 'any') {
+    endpointKey = EXTENSION_TO_ENDPOINT['any']?.[toExtension];
+  }
+  
+  return endpointKey || '';
+};
+
+/**
+ * Resolves the full endpoint URL for a given conversion
+ */
+export const getEndpointUrl = (fromExtension: string, toExtension: string): string => {
+  const endpointName = getEndpointName(fromExtension, toExtension);
+  if (!endpointName) return '';
+  
+  // Find the endpoint URL from CONVERSION_ENDPOINTS using the endpoint name
+  for (const [key, endpoint] of Object.entries(CONVERSION_ENDPOINTS)) {
+    if (ENDPOINT_NAMES[key as keyof typeof ENDPOINT_NAMES] === endpointName) {
+      return endpoint;
+    }
+  }
+  return '';
+};
+
+/**
+ * Checks if a conversion is supported
+ */
+export const isConversionSupported = (fromExtension: string, toExtension: string): boolean => {
+  return getEndpointName(fromExtension, toExtension) !== '';
+};
+
+/**
+ * Checks if the given extension is an image format
+ */
+export const isImageFormat = (extension: string): boolean => {
+  return ['png', 'jpg', 'jpeg', 'gif', 'tiff', 'bmp', 'webp', 'svg'].includes(extension.toLowerCase());
+};
+
+/**
+ * Checks if the given extension is a web format
+ */
+export const isWebFormat = (extension: string): boolean => {
+  return ['html', 'zip'].includes(extension.toLowerCase());
+};
+
+/**
+ * Gets available target extensions for a given source extension
+ * Extracted from useConvertParameters to be reusable in automation settings
+ */
+export const getAvailableToExtensions = (fromExtension: string): Array<{value: string, label: string, group: string}> => {
+  if (!fromExtension) return [];
+
+  // Handle dynamic format identifiers (file-<extension>)
+  if (fromExtension.startsWith('file-')) {
+    // Dynamic format - use 'any' conversion options (file-to-pdf)
+    const supportedExtensions = CONVERSION_MATRIX['any'] || [];
+    return TO_FORMAT_OPTIONS.filter(option =>
+      supportedExtensions.includes(option.value)
+    );
+  }
+
+  let supportedExtensions = CONVERSION_MATRIX[fromExtension] || [];
+
+  // If no explicit conversion exists, but file-to-pdf might be available,
+  // fall back to 'any' conversion (which converts unknown files to PDF via file-to-pdf)
+  if (supportedExtensions.length === 0 && fromExtension !== 'any') {
+    supportedExtensions = CONVERSION_MATRIX['any'] || [];
+  }
+
+  return TO_FORMAT_OPTIONS.filter(option =>
+    supportedExtensions.includes(option.value)
+  );
+};