Add TECH_STACK.md documentation

[Copilot]

Description

Adds TECH_STACK.md documenting the complete technology stack used in BentoPDF.

Coverage:

• Core languages: TypeScript, JavaScript, HTML, CSS/TailwindCSS
• Build tooling: Vite, Node.js, npm
• PDF libraries: pdf-lib, pdfjs-dist, pdfkit, jspdf, qpdf-wasm
• Document conversion: LibreOffice converter, markdown-it, xlsx, papaparse
• Image processing: html2canvas, cropperjs, tesseract.js, TIFF/HEIC handlers
• Testing: Vitest, @testing-library/dom
• Linting: ESLint, Prettier, Husky, lint-staged
• Deployment: Docker, Kubernetes/Helm, Cloudflare Workers
• Runtime: WebAssembly modules, Web Workers
• i18n: i18next
• Documentation: VitePress

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

🧪 How Has This Been Tested?

Checklist:

• Verified output manually
• Tested with relevant sample documents or data
• Wrote Vite Test Case (if applicable)

Expected Results:

• TECH_STACK.md file exists at repository root with comprehensive technology stack documentation

Actual Results:

• 202-line markdown document created with all technologies, libraries, and tools catalogued with version numbers

Checklist:

• I have signed the Contributor License Agreement (CLA) or my organization has signed the Corporate CLA
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Original prompt

Create a documentational list called TECH_STACK.md in markdown format of the technologic stack and computer languages used in this project.

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[github-actions]

CLA Signature Required

Thank you for your contribution! Before we can accept your pull request, you need to sign our Contributor License Agreement (CLA).

Why do we need a CLA?

BentoPDF uses a dual licensing model (AGPL-3.0 for open source + commercial license). The CLA allows us to:

• Include your contributions in both open source and commercial versions
• Protect you and us legally
• Keep the project sustainable

How to sign

To sign the CLA, please comment on this PR with:

I have read the CLA Document and I hereby sign the CLA

For corporate contributions, please have your organization sign our Corporate CLA (CCLA) by contacting us at contact@bentopdf.com.

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⚠️ Note: You only need to sign the CLA once. Future contributions to this repository will not require re-signing.

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I have read the CLA Document and I hereby sign the CLA

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_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}