[V2] feat(redaction): implement PDFium-based redaction service and CLI tool

[balazs-szucs]

Description of Changes

This pull request introduces support for PDF redaction using PDFium, refines the text search and bounding logic in the TextFinder class, and updates configuration and API models to accommodate these changes. The main themes are: enabling PDFium-based redaction (including configuration and process management), improving text search accuracy, and updating related API models.

PDFium Redactor Integration and Configuration:

• Added PDFIUM_REDACTOR as a new Processes enum value and integrated it into the process execution logic, including session limit and timeout retrieval in ProcessExecutor and corresponding properties in ApplicationProperties.
• Introduced a new value class PdfiumRedactionRegion to represent redaction regions for PDFium-based redaction.

Text Search and Bounding Improvements:

• Refactored the TextFinder class: extracted search pattern construction and bounding box calculation into helper methods and classes, improved fallback logic for missing position data, and enhanced debug logging. The PDFText model now includes fontSize.

API Model and Defaults Updates:

• Updated RedactPdfRequest: clarified the description and default value for listOfText, and changed the default for convertPDFToImage to true.

These changes collectively enable robust PDF redaction capabilities using PDFium, improve the accuracy of text search and bounding, and ensure the API and configuration are up to date with these enhancements.

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Checklist

General

• I have read the Contribution Guidelines
• I have read the Stirling-PDF Developer Guide (if applicable)
• I have read the How to add new languages to Stirling-PDF (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 (if functionality has heavily changed)
• I have read the section 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 for more details.

[Copilot]

Pull request overview

This PR introduces PDFium-based redaction capabilities to enhance PDF text removal accuracy, refactors text search logic for better performance, and updates API models. The implementation adds a Node.js CLI tool that interfaces with PDFium's WASM binary, a new Java service to manage PDFium processes, and modernizes the redaction controller to use parallel processing with retry logic for handling text reflow in tables.

Key Changes:

• Added PDFium integration with Node.js CLI tool (redact.cjs) and Java service (PdfiumRedactionService) for native PDF text removal
• Refactored TextFinder class to extract pattern building and bounds calculation into dedicated helper methods/classes, added font size tracking to PDFText model
• Updated RedactController to implement parallel text searching, PDFium-first redaction with fallback to PDFBox overlays, and retry logic for stubborn text matches

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
frontend/scripts/pdfium/redact.cjs	New Node.js CLI tool for PDFium-based redaction with WASM integration
frontend/eslint.config.mjs	Added .cjs extension to ESLint configuration for new script
RedactControllerTest.java	Extensive test updates including PDFium mocking, parallel processing tests, removed content stream tests
WidthCalculator.java	Deleted - width calculation logic no longer needed with PDFium approach
TextFinderUtils.java	Deleted - pattern creation moved to TextFinder
TextEncodingHelper.java	Deleted - encoding validation no longer required with PDFium
PdfiumRedactionService.java	New service managing PDFium environment, process execution, and coordinate conversion
TextFinder.java	Refactored to extract pattern/bounds logic into helper classes, added font size tracking
RedactPdfRequest.java	Updated API documentation and changed default for convertPDFToImage to true
PdfiumRedactionRegion.java	New value class representing PDFium redaction regions
PDFText.java	Added fontSize field for improved bounding calculations
RedactController.java	Major refactor: parallel processing, PDFium integration, retry logic, page rotation handling
InitialSetup.java	Minor whitespace cleanup
ProcessExecutor.java	Added PDFIUM_REDACTOR process type with session limits and timeout configuration
ApplicationProperties.java	Added configuration properties for PDFium redactor session limits and timeouts

Comments suppressed due to low confidence (1)

app/core/src/main/java/stirling/software/SPDF/controller/api/security/RedactController.java:82

• The method 'redactPDF' may be confused with redactPdf.

    public ResponseEntity<byte[]> redactPDF(@ModelAttribute ManualRedactPdfRequest request)

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[balazs-szucs]

On hold due to embedPDF V2

[christaikobo]

Sorry to be bugging you again, is this the continuation of #4240?

[Frooodle]

already done?