feat: add browser implementations for advanced tools

frontend/src/components/tools/addPageNumbers/AddPageNumbersPositionSettings.tsx

@@ -2,7 +2,7 @@
  * AddPageNumbersPositionSettings - Position & Pages step
  */
 
-import { Stack, TextInput, NumberInput, Divider, Text } from "@mantine/core";
+import { Stack, TextInput, NumberInput, Divider, Text, SegmentedControl } from "@mantine/core";
 import { useTranslation } from "react-i18next";
 import { AddPageNumbersParameters } from "./useAddPageNumbersParameters";
 import { Tooltip } from "../../shared/Tooltip";
@@ -27,6 +27,27 @@ const AddPageNumbersPositionSettings = ({
 
   return (
     <Stack gap="lg">
+      <Stack gap="xs">
+        <Text size="sm" fw={500}>
+          {t('addPageNumbers.processingMode.label', 'Processing mode')}
+        </Text>
+        <SegmentedControl
+          value={parameters.processingMode}
+          onChange={(value) => onParameterChange('processingMode', value as AddPageNumbersParameters['processingMode'])}
+          data={[
+            { label: t('addPageNumbers.processingMode.backend', 'Backend'), value: 'backend' },
+            { label: t('addPageNumbers.processingMode.frontend', 'Browser'), value: 'frontend' }
+          ]}
+          fullWidth
+          disabled={disabled}
+        />
+        <Text size="xs" c="dimmed">
+          {parameters.processingMode === 'frontend'
+            ? t('addPageNumbers.processingMode.frontendDescription', 'Stamp page numbers locally (page lists only).')
+            : t('addPageNumbers.processingMode.backendDescription', 'Use the server for formula-based selection and heavy PDFs.')}
+        </Text>
+      </Stack>
+
       {/* Position Selection */}
       <Stack gap="md">
         <PageNumberPreview

frontend/src/components/tools/addPageNumbers/useAddPageNumbersOperation.ts

@@ -1,7 +1,9 @@
 import { useTranslation } from 'react-i18next';
-import { ToolType, useToolOperation } from '../../../hooks/tools/shared/useToolOperation';
+import { ToolType, useToolOperation, ToolOperationConfig } from '../../../hooks/tools/shared/useToolOperation';
 import { createStandardErrorHandler } from '../../../utils/toolErrorHandler';
 import { AddPageNumbersParameters, defaultParameters } from './useAddPageNumbersParameters';
+import { addPageNumbersClientSide } from '../../../utils/pdfOperations/addPageNumbers';
+import { validatePageNumbers } from '../../../utils/pageSelection';
 
 export const buildAddPageNumbersFormData = (parameters: AddPageNumbersParameters, file: File): FormData => {
   const formData = new FormData();
@@ -23,7 +25,18 @@ export const addPageNumbersOperationConfig = {
   operationType: 'addPageNumbers',
   endpoint: '/api/v1/misc/add-page-numbers',
   defaultParameters,
-} as const;
+  frontendProcessing: {
+    process: addPageNumbersClientSide,
+    shouldUseFrontend: (params) => {
+      if (params.processingMode !== 'frontend') return false;
+      const selection = params.pagesToNumber?.trim();
+      if (!selection) return true;
+      if (selection.toLowerCase().includes('n')) return false;
+      return validatePageNumbers(selection);
+    },
+    statusMessage: 'Adding page numbers in browser...'
+  }
+} as const satisfies ToolOperationConfig<AddPageNumbersParameters>;
 
 export const useAddPageNumbersOperation = () => {
   const { t } = useTranslation();

frontend/src/components/tools/addPageNumbers/useAddPageNumbersParameters.ts

@@ -1,7 +1,7 @@
-import { BaseParameters } from '../../../types/parameters';
+import { BaseParameters, ToggleableProcessingParameters } from '../../../types/parameters';
 import { useBaseParameters, type BaseParametersHook } from '../../../hooks/tools/shared/useBaseParameters';
 
-export interface AddPageNumbersParameters extends BaseParameters {
+export interface AddPageNumbersParameters extends BaseParameters, ToggleableProcessingParameters {
   customMargin: 'small' | 'medium' | 'large' | 'x-large';
   position: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9;
   fontSize: number;
@@ -19,6 +19,7 @@ export const defaultParameters: AddPageNumbersParameters = {
   startingNumber: 1,
   pagesToNumber: '',
   customText: '',
+  processingMode: 'backend',
 };
 
 export type AddPageNumbersParametersHook = BaseParametersHook<AddPageNumbersParameters>;
@@ -26,7 +27,7 @@ export type AddPageNumbersParametersHook = BaseParametersHook<AddPageNumbersPara
 export const useAddPageNumbersParameters = (): AddPageNumbersParametersHook => {
   return useBaseParameters<AddPageNumbersParameters>({
     defaultParameters,
-    endpointName: 'add-page-numbers',
+    endpointName: (params) => (params.processingMode === 'frontend' ? '' : 'add-page-numbers'),
     validateFn: (params): boolean => {
       return params.fontSize > 0 && params.startingNumber > 0;
     },